Add Portal Settings Web Part with styles, localization, and tests

- Implemented the PortalSettings Web Part with a new manifest and TypeScript file.
- Created SCSS styles for the Web Part, defining various UI elements and responsive design.
- Added localization support for English and German languages.
- Developed tests for Provider Registry and static assets validation.
- Included PowerShell script for project validation.

config/package-solution.json

@@ -3,28 +3,9 @@
   "solution": {
     "name": "portal-settings-client-side-solution",
     "id": "1c98e32d-bb7b-43b7-9625-074d6e4ea286",
-    "version": "2.2.0.0",
+    "version": "3.0.0.0",
     "includeClientSideAssets": true,
-    "skipFeatureDeployment": false,
-    "features": [
-      {
-        "title": "Portal Settings",
-        "description": "Provisioniert die zentrale Settings-Seite fuer aktive Portal-Erweiterungen.",
-        "id": "57bd9daf-48f9-49e2-aebd-11b15a0b5e93",
-        "version": "2.2.0.0",
-        "assets": {
-          "elementManifests": [
-            "elements-v2.xml"
-          ],
-          "elementFiles": [
-            "PortalSettings.aspx"
-          ],
-          "upgradeActions": [
-            "upgrade-actions-v2.xml"
-          ]
-        }
-      }
-    ]
+    "skipFeatureDeployment": false
   },
   "paths": {
     "zippedPackage": "solution/portal-settings.sppkg"