feat: Implement tool for parallel execution (#2009)

Fixes #2001

### Parallel execution algorithm

* [README.md](https://github.com/Flank/flank/blob/2001_Implement_tool_for_parallel_execution/tool/execution/parallel/README.md)

#### Example graph execution

![example-graph](http://www.plantuml.com/plantuml/proxy?cache=no&fmt=svg&src=https://raw.githubusercontent.com/Flank/flank/2001_Implement_tool_for_parallel_execution/docs/hld/parallel-example-graph.puml)

#### Algorithm

![parallel-execution](http://www.plantuml.com/plantuml/proxy?cache=no&fmt=svg&src=https://raw.githubusercontent.com/Flank/flank/2001_Implement_tool_for_parallel_execution/docs/hld/parallel-execution.puml)

#### Functions

![parallel-execution](http://www.plantuml.com/plantuml/proxy?cache=no&fmt=svg&src=https://raw.githubusercontent.com/Flank/flank/2001_Implement_tool_for_parallel_execution/docs/hld/parallel-execution-api-functions.puml)

#### Types

![parallel-execution](http://www.plantuml.com/plantuml/proxy?cache=no&fmt=svg&src=https://raw.githubusercontent.com/Flank/flank/2001_Implement_tool_for_parallel_execution/docs/hld/parallel-execution-api-structures.puml)

### Different graph states

![parallel-execution](http://www.plantuml.com/plantuml/proxy?cache=no&fmt=svg&src=https://raw.githubusercontent.com/Flank/flank/2001_Implement_tool_for_parallel_execution/docs/hld/task-graph.puml)

## Test Plan
> How do we know the code works?

Unit tests are passing.

## Checklist

- [x] Documented
- [x] Unit tested

docs/hld/parallel-example-graph.puml

@@ -0,0 +1,52 @@
+@startuml
+'https://plantuml.com/component-diagram
+skinparam componentStyle rectangle
+
+component Finalize
+
+component NotifyRemoteServices
+component GenerateReport
+
+component CalculateResults
+
+component PerformExecution
+
+component CollectRemoteData1
+component FetchPreviousResults
+
+component InitialCalculations
+component RunRemoteProcess1
+component RunRemoteProcess2
+
+component CollectLocalData2
+component CollectLocalData1
+component Authorize
+
+Finalize *--> GenerateReport
+Finalize *--> NotifyRemoteServices
+
+GenerateReport *--> CalculateResults
+NotifyRemoteServices *--> CalculateResults
+
+CalculateResults *--> PerformExecution
+CalculateResults *--> FetchPreviousResults
+
+InitialCalculations *--> CollectLocalData1
+InitialCalculations *--> CollectLocalData2
+
+PerformExecution *--> CollectRemoteData1
+PerformExecution *---> InitialCalculations
+
+FetchPreviousResults *--> Authorize
+
+InitialCalculations -[hidden]r- RunRemoteProcess1
+
+CollectRemoteData1 *--> RunRemoteProcess1
+CollectRemoteData1 *--> RunRemoteProcess2
+
+RunRemoteProcess1 *--> Authorize
+RunRemoteProcess2 *--> Authorize
+RunRemoteProcess2 -[hidden]r- FetchPreviousResults
+
+
+@enduml

docs/hld/parallel-execution-api-functions.puml

@@ -0,0 +1,59 @@
+@startuml
+'left to right direction
+package "parallel" {
+
+object "Parallel.Function.invoke()" as Function {
+creates
+}
+
+class "Parallel.Task" as Task<R>
+class "Parallel.Task.Signature" as Task_Signature<R>
+interface "Parallel.Type<R>" as Type
+interface "Parallel.Type<R>" as Type2
+interface ExecuteTask<R> << (T, orchid) >>
+interface ParallelState << (T, orchid) >>
+
+object "using" as usingType {
+creates
+}
+object "using" as usingSignature {
+creates
+}
+object from {
+creates
+}
+
+object "invoke()" as invokeExecution {
+executes
+}
+object "invoke()" as reduce {
+reduces
+}
+
+ExecuteTask <. "1" Function
+
+ExecuteTask <--o "1" usingSignature
+usingSignature "1" #--> Task_Signature
+usingSignature  "1" ..> Task
+usingSignature -right-* usingType
+
+Type <--# "1" usingType
+ExecuteTask <--o "1" usingType
+usingType "1" ..> Task
+usingType *-left- from
+
+Type <--# "1" from
+Type <--o "*" from
+from "1" ..> Task_Signature
+
+Type2 <--o "*" reduce
+Task <. "*" reduce
+Task <-# "*" reduce
+
+Task <--# "*" invokeExecution
+
+invokeExecution "*" .left.> ParallelState
+invokeExecution "1" o-left-> ParallelState
+
+}
+@enduml

docs/hld/parallel-execution-api-structures.puml

@@ -0,0 +1,56 @@
+@startuml
+package "parallel" {
+class "Parallel.Context" as Context {
+out: Output?
+}
+class "Parallel.Task" as Task<R> {
+signature: Signature<R>
+execute: ExecuteTask<R>
+}
+class "Parallel.Task.Signature" as Signature<R>{
+returns: Type<R>
+args: Set<Type<*>>
+}
+class "Parallel.Function" as Function<X: ParallelContext> {
+context: () -> X
+= suspend <R> (ExecuteTaskInContext) -> ExecuteTask
+}
+interface "Any data" as Data << (R, yellow) >>
+interface ExecuteTask<R> << (T, orchid) >> {
+= suspend ParallelState.() -> R
+}
+interface ExecuteTaskInContext<X: Parallel.Context> << (T, orchid) >> {
+= suspend X.() -> R
+}
+interface "Parallel.Type" as Type <T>
+interface ParallelState << (T, orchid) >> {
+= Map<Parallel.Type<*>, Any>
+}
+interface Output << (T, orchid) >> {
+= Any.() -> Unit
+}
+
+Function ..> ExecuteTask
+Function #.. ExecuteTaskInContext
+
+ExecuteTaskInContext #.. Context
+ExecuteTaskInContext .> Data
+
+Data <. ExecuteTask
+Data "*" --o "1" ParallelState
+
+ExecuteTask "1" -* "1" Task
+ExecuteTask #.. ParallelState
+
+Context --|> Type
+Context "0..1" o..> "1" Output
+
+ParallelState "1" -o "1" Context
+ParallelState "1" o- "*" Type
+
+Task "1" *-- "1" Signature
+
+Type "1" -* "1" Signature
+Type "*" -o "1" Signature
+
+@enduml

docs/hld/parallel-execution.puml

@@ -0,0 +1,65 @@
+@startuml
+skinparam ConditionEndStyle hline
+
+|Invoke execution|
+split
+-[hidden]->
+start
+:arguments;
+:initial state;
+repeat :Handle state}
+-[dotted]->
+if (is channel closed for receive?) then
+stop
+else (no)
+endif
+:next result<
+if (on first error) then (true)
+:Abort execution}
+else (false)
+endif
+repeat while (accumulate result)
+detach
+
+|Handle state|
+split again
+-[hidden]->
+if (is complete) then (yes)
+:close channel/
+elseif (is finished) then (yes)
+:nothing to do;
+detach
+else
+:filter tasks for current state;
+:group them by arguments;
+repeat :prepare properties|
+repeat :Execute task}
+repeat while (for each task)
+repeat while (for each group)
+endif
+detach
+
+|Execute task|
+split again
+-[hidden]->
+partition async {
+:log start;
+:prepare context;
+if (execute task in context) then (try)
+:log success;
+else (catch)
+:log exception;
+endif
+:send result]
+detach
+}
+
+|Abort execution|
+split again
+-[hidden]->
+:cancel scope;
+repeat :send "not started"]
+repeat while (for each remaining task)
+:close channel/
+detach
+@enduml

docs/hld/task-graph.puml

@@ -0,0 +1,119 @@
+@startuml
+package "Valid graph" {
+map H1 #lightgreen {
+}
+map I1 #lightgreen {
+}
+map F1 #lightgreen {
+I1 *--> I1
+}
+map E1 #lightgreen {
+I1 *--> I1
+}
+map D1 #lightgreen {
+I1 *--> I1
+}
+map C1 #lightgreen {
+D1 *--> D1
+}
+map B1 #lightgreen {
+C1 *-> C1
+E1 *--> E1
+H1*---> H1
+}
+map A1 #lightgreen {
+B1 *--> B1
+F1 *--> F1
+C1 *--> C1
+I1 *--> I1
+}
+}
+package "Selected graph" {
+map H2 #lightgreen {
+}
+map I2 #lightgreen {
+}
+map F2 #lightgrey {
+I2 *--> I2
+}
+map E2 #lightgreen {
+I2 *--> I2
+}
+map D2 #lightgreen {
+I2 *--> I2
+}
+map C2 #lightgreen {
+D2 *--> D2
+}
+map B2 #lightblue {
+C2 *-> C2
+E2 *--> E2
+H2*---> H2
+}
+map A2 #lightgrey {
+B2 *--> B2
+F2 *--> F2
+C2 *--> C2
+I2 *--> I2
+}
+}
+package "Broken graph" {
+map H3 #lightgreen {
+}
+map I3 #black {
+}
+map F3 #red {
+I3 *--> I3
+}
+map E3 #red {
+I3 *--> I3
+}
+map D3 #red {
+I3 *--> I3
+}
+map C3 #yellow {
+D3 *--> D3
+}
+map B3 #yellow {
+C3 *-> C3
+E3 *--> E3
+H3*---> H3
+}
+map A3 #yellow {
+B3 *--> B3
+F3 *--> F3
+C3 *--> C3
+I3 *--> I3
+}
+}
+
+package "Failed graph" {
+map H4 #lightgreen {
+}
+map I4 #lightgreen {
+}
+map F4 #red {
+I4 *--> I4
+}
+map E4 #yellow {
+I4 *--> I4
+}
+map D4 #yellow {
+I4 *--> I4
+}
+map C4 #lightgrey {
+D4 *--> D4
+}
+map B4 #lightgrey {
+C4 *-> C4
+E4 *--> E4
+H4*---> H4
+}
+map A4 #lightgrey {
+B4 *--> B4
+F4 *--> F4
+C4 *--> C4
+I4 *--> I4
+}
+}
+@enduml

settings.gradle.kts

@@ -31,6 +31,8 @@ include(
     ":tool:junit",
     ":tool:log",
     ":tool:log:format",
+    ":tool:execution:parallel",
+    ":tool:execution:synchronized",
 )
 
 plugins {