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.

tests/tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "outDir": "../temp/tests",
+    "skipLibCheck": true,
+    "types": [],
+    "lib": ["es5", "dom", "es2015.collection"]
+  },
+  "files": [
+    "../src/core/ProviderContracts.ts",
+    "../src/core/ObjectPath.ts",
+    "../src/providers/MegaMenuSettingsProvider.ts",
+    "../src/providers/CustomBrandingSettingsProvider.ts",
+    "../src/providers/ExpiryIndicatorSettingsProvider.ts",
+    "../src/providers/ProviderRegistry.ts",
+    "./ProviderRegistry.test.ts"
+  ]
+}