feat: Add custom branding functionality with CSS and JSON configuration

- Introduced custom branding CSS styles in `custom-branding.css`.
- Created example JSON configuration for custom branding in `custom-branding.example.json`.
- Implemented branding configuration logic in `BrandingConfig.ts` to normalize and validate branding settings.
- Developed CSS loader to manage loading and unloading of custom stylesheets in `BrandingCssLoader.ts`.
- Added DOM rendering capabilities for branding elements in `BrandingDomRenderer.ts`.
- Defined types and interfaces for branding elements and configurations in `BrandingTypes.ts`.
- Included localization support for German in `de-de.js`.
- Added unit tests for branding configuration, CSS loader, and DOM renderer.
- Validated project structure and static assets with new validation scripts.

tests/tsconfig.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "outDir": "../temp/tests",
+    "skipLibCheck": true,
+    "types": [],
+    "lib": ["es5", "dom", "es2015.collection"]
+  },
+  "files": [
+    "../src/extensions/customBranding/BrandingTypes.ts",
+    "../src/extensions/customBranding/BrandingConfig.ts",
+    "../src/extensions/customBranding/BrandingDomRenderer.ts",
+    "../src/extensions/customBranding/BrandingCssLoader.ts"
+  ]
+}