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.

src/webparts/accordion/AccordionWebPart.manifest.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://developer.microsoft.com/json-schemas/spfx/client-side-web-part-manifest.schema.json",
+  "id": "18e20eee-2838-4032-8c9d-697e52099059",
+  "alias": "AccordionWebPart",
+  "componentType": "WebPart",
+  "version": "*",
+  "manifestVersion": 2,
+  "requiresCustomScript": false,
+  "preconfiguredEntries": [{
+    "groupId": "5c03119e-3074-46fd-976b-c60198311f70",
+    "group": { "default": "Other", "de-de": "Weitere" },
+    "title": { "default": "Accordion", "de-de": "Akkordeon" },
+    "description": {
+      "default": "Displays SharePoint list items as an accessible accordion.",
+      "de-de": "Zeigt Einträge einer SharePoint-Liste als barrierearmes Akkordeon an."
+    },
+    "officeFabricIconFontName": "BulletedList2",
+    "properties": {
+      "listId": "",
+      "titleField": "Title",
+      "contentField": "",
+      "categoryField": "",
+      "sortField": "Title",
+      "sortAscending": true,
+      "allowMultiple": false,
+      "initialState": "collapsed",
+      "showCategories": true
+    }
+  }]
+}