Bug in new Salsa pretty-printed stack traces: wrong stack traces

[NHDaly]

The salsa pretty stack trace is currently off-by-one, skipping the first function called and duplicating the last one:

julia> using Salsa

julia> @derived f(rt, x) = g(rt, x)
f (generic function with 1 method)

julia> @derived g(rt, x) = h(rt, x)
g (generic function with 1 method)

julia> @derived h(rt, _) = error("OH NO")
h (generic function with 1 method)

julia> f(Runtime(), 1)
ERROR: SalsaWrappedException: Error encountered while executing Salsa derived function:
OH NO

------ Salsa Trace -----------------
[1] @derived f(::Runtime, 1::Any)
[2] @derived g(::Runtime, 1::Any)
[3] @derived h(::Runtime, 1::Any)
------------------------------------

Stacktrace:
 [1] error(::String) at ./error.jl:33
 [2] %%__user_h(::Salsa._TracingRuntime{Salsa.EmptyContext,Salsa._DefaultSalsaStorage.DefaultStorage}, ::Int64) at ./REPL[16]:1
 [3] invoke_user_function(::Salsa._TracingRuntime{Salsa.EmptyContext,Salsa._DefaultSalsaStorage.DefaultStorage}, ::Salsa.DerivedKey{typeof(h),Tuple{Any}}, ::Int64) at /Users/daly/julia-dev/Salsa/src/Salsa.jl:612
...

Also, I feel like we're maybe printing the stack backwards? I'm not sure what's best - it kind of makes sense to print top-down since that's like the order of the demand, but usually stack traces are printed the other way. I kind of like though that you can just scroll to the middle and read both the pretty stack trace for the current frame and the julia stack frame of the failure, so that's kind of nice?

[NHDaly]

CC: @comnik for your opinion on the printing order...

Regarding the best order to print them in, it's not hard to change, we just need to pick. Some reasonable options:

• Currently (demand-first):

  ------ Salsa Trace -----------------
  [1] @derived f(::Runtime, 1::Any)
  [2] @derived g(::Runtime, 1::Any)
  [3] @derived h(::Runtime, 1::Any)
  ------------------------------------

• Same order reversed numbering:

  ------ Salsa Trace -----------------
  [3] @derived f(::Runtime, 1::Any)
  [2] @derived g(::Runtime, 1::Any)
  [1] @derived h(::Runtime, 1::Any)
  ------------------------------------

• Inside out (standard stacktrace order):

  ------ Salsa Trace -----------------
  [1] @derived h(::Runtime, 1::Any)
  [2] @derived g(::Runtime, 1::Any)
  [3] @derived f(::Runtime, 1::Any)
  ------------------------------------

[comnik]

@rai-nhdaly Let's run with the order we have for a bit and figure out how it works in practice?