.Net: Process mermaid flowchart code generation, image generation on flowchart and sample usage.

[joslat]

I propose adding functionality to render workflows/processes as visual diagrams, using Markdown (Mermaid syntax) and generating images. This feature would greatly aid in documenting and communicating process flows within the framework.

Motivation and Context

Why: Improved visualization and understanding of the workflow, reduce cognitive load and also it makes it cooler.
So we can visualize the Process Workflow in Step 01 (Step01_Processes) like this

Source and example (once merged): https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/GettingStartedWithProcesses/Step01/Step01_Processes.cs

And the "Fried Fish Preparation Process" looks like this:

And like this if we set the nesting to 1 (no nesting), so it does not go into a subprocess (a step which is a KernelProcess):

Source and example: https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/GettingStartedWithProcesses/Step03/Step03a_FoodPreparation.cs

Problem solved:
Eases understanding complex workflows, helps to validate your workflow and to improve it. Makes understanding FASTER.

Scenario: All scenarios
Related issue: #9514

Existing issue:
Usually a Step (node) has edges to other Steps which is OK.
But, in case of a Step which is a Process (ie, composed of other steps), This Step can have an Edge to an Inner Step, which makes no sense. After a great discussion with the team, @alliscode and @esttenorio (thanks a ton for the great interaction and discussion) this is done at the moment to represent Entry Steps, where the workflow is starting on the Process Step.

This made it impossible to draw this properly and is ignored, but upon discovery it was rendered like this for reference:

And if we debug the Edges of the Step which is a Process, we see it has two, the second one properly formed is the exit Edge but the first one on the Edge Key it does not have a properly formed EventId but a simple name:

This comes from the entry point defined next (Thanks @esttenorio for finding it):

Here is there the root process steps "links" with the internal steps of the nested process.

Which works, but we end up with a Edge from an "event" (FriedFishProcess.ProcessEvents.PrepareFriedFish) to an Internal Step.
The biggest problem here is that the Event is parentless, not associated to a Step. So, we cannot "paint" the graph to depict where does it come from.
The technical solution is to attach the Edge to the target Step, but it has no parent.

Proposal: Make all Events with a Single Parent. One Event, One Parent, point. And associate the events to that parent through an Edge. so we know where it starts and where it ends(goes). This way will enable proper tooling and accurate rendering - and the inherent graph will not try to "trick us".
(I will create an issue for this)

Solution:
At the moment we are identifying and ignoring those Edges.

Description

Added ProcessVisualizationExtensions.cs in Process.Core to render the markdown at the core, next to the ProcessBuilder, as an extension method to it.
Updated Sample 01 to showcase example, also added the MermaidRenderer.cs to render an image of this mermaid code by using PuppeteerSharp, which had to be added to the GettingStartedWithProcesses.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄