[http-client-csharp] add regen preview local validation script (#8819)

This PR adds a new regen preview developer script to aid in testing and
validating changes made to the generator. It allows regenerating azure
libraries locally using the local artifacts of the generator, helping to
see what the regenerated code will look like with the applied changes.

contributes to: Azure/azure-sdk-for-net#52234

example run:
<img width="539" height="310" alt="image"
src="https://github.com/user-attachments/assets/b1151f24-bac6-49b9-84b9-9c4352c0c71e"
/>

Author: jorgerangel-msft

.gitignore

@@ -217,6 +217,7 @@ packages/*/etc/
 # csharp emitter
 !packages/http-client-csharp/package-lock.json
 packages/http-client-csharp/generator/artifacts/
+packages/http-client-csharp/debug/
 packages/http-client-csharp/generated-defs/**/*.js
 packages/http-client-csharp/generated-defs/**/*.js.map
 packages/http-client-csharp/generated-defs/**/*.d.ts

cspell.yaml

@@ -6,6 +6,8 @@ dictionaries:
   - typescript
 words:
   - Adoptium
+  - Arize
+  - arizeaiobservabilityeval
   - agentic
   - aiohttp
   - alzimmer
@@ -156,11 +158,13 @@ words:
   - myname
   - mypy
   - nanos
+  - ncpu
   - nexted
   - nihao
   - nint
   - NODEFS
   - noformat
+  - nologo
   - noopener
   - noreferrer
   - nosec

packages/http-client-csharp/CONTRIBUTING.md

@@ -177,11 +177,21 @@ Generate test projects to validate the emitter and generator:
 
 To regenerate test projects after making changes:
 
-1. **Generate projects**:
+**Generate projects**:
 
-   ```bash
-   ./eng/scripts/Generate.ps1
-   ```
+```bash
+./eng/scripts/Generate.ps1
+```
+
+### Regenerating Azure Libraries
+
+To regenerate azure libraries using your local changes, run:
+
+```bash
+   ./eng/scripts/RegenPreview.ps1 <path-to-clone-of-azure-sdk-for-net>
+```
+
+This will regenerate all the Azure libraries and allow you to view any potential diffs your changes may cause. For more information on the script's usage, see [RegenPreview](./eng/scripts/docs/RegenPreview.md).
 
 ## Validating Changes Against the Azure Generator