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/copy-assets.json

@@ -1,4 +0,0 @@
-{
-  "$schema": "https://developer.microsoft.com/json-schemas/spfx-build/copy-assets.schema.json",
-  "deployCdnPath": "temp/deploy"
-}