.Net: Visualizing dotnet workflows (#882)

* Adding more test for workflow vizualization.

* Improving README for sample.

* More cleanup.

* Removing rendering of workflow visualization and adding basic support for mermaid format.

* Adding basic mermaid tests.

* Improving sample. Switching to another branch.

* About to merge from main.

* Formatting.

* More fromatting.

* Removng uneeded call to ToUpper.

* Adding README.

* Moving samples under workflow to workflows.

* Removing uneeded README for map-reduce sample.

dotnet/samples/GettingStarted/Workflows/Visualization/README.md

@@ -0,0 +1,43 @@
+# Workflow Visualization Sample
+
+This sample demonstrates how to visualize workflows using `ToMermaidString()` and `ToDotString()` extension methods. It uses a map-reduce workflow with fan-out/fan-in patterns as an example.
+
+## Running the Sample
+
+```bash
+dotnet run
+```
+
+## Output Formats
+
+The sample generates two visualization formats:
+
+### Mermaid
+Paste the output into any Mermaid-compatible viewer (GitHub, Mermaid Live Editor, etc.):
+
+![Mermaid Visualization](Resources/mermaid_render.png)
+
+### DOT (Graphviz)
+Render with Graphviz (requires `graphviz` to be installed):
+
+```bash
+dotnet run | tail -n +20 | dot -Tpng -o workflow.png
+```
+
+![Graphviz Visualization](Resources/graphviz_render.png)
+
+## Usage
+
+```csharp
+Workflow workflow = BuildWorkflow();
+
+// Generate Mermaid format
+string mermaid = workflow.ToMermaidString();
+
+// Generate DOT format
+string dotString = workflow.ToDotString();
+```
+
+## Related Samples
+
+- [Map-Reduce Workflow Sample](../../../Workflows/Visualization/README.md): The workflow implementation being visualized