Add Accordion web part implementation with dynamic SharePoint list integration

- Created Accordion web part with SPFx 1.4.1 framework.
- Implemented dynamic loading of SharePoint lists and fields.
- Added configuration options for title, content, and category fields.
- Included support for multiple open sections and initial state settings.
- Developed HTML sanitizer for rich text content.
- Implemented accessible accordion UI with category grouping.
- Added localization support for English and German languages.
- Created necessary configuration files for deployment and asset management.
- Added validation script to ensure project compliance with standards.

config/serve.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://developer.microsoft.com/json-schemas/core-build/serve.schema.json",
+  "port": 4321,
+  "https": true,
+  "initialPage": "https://localhost:5432/workbench",
+  "api": {
+    "port": 5432,
+    "entryPath": "node_modules/@microsoft/sp-webpart-workbench/lib/api/"
+  }
+}
+