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.

src/index.ts

@@ -1 +1,2 @@
-// A file is required to be in the root of the /src directory by the TypeScript compiler
+export * from './core/ProviderContracts';
+export * from './providers/ProviderRegistry';