Add Current Navigation Application Customizer

- Created a new SPFx Application Customizer for current navigation.
- Implemented core functionality to fetch and render navigation items from a SharePoint term set.
- Added styles for the navigation component using SCSS.
- Included localization support for English and German languages.
- Developed unit tests for core navigation functionalities.
- Configured TypeScript and TSLint settings for the project.
- Added validation scripts for static assets and package configuration.

tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "target": "es5", "forceConsistentCasingInFileNames": true, "module": "esnext",
+    "moduleResolution": "node", "declaration": true, "sourceMap": true,
+    "experimentalDecorators": true, "skipLibCheck": true,
+    "typeRoots": ["./node_modules/@types", "./node_modules/@microsoft"],
+    "types": ["es6-promise", "webpack-env"],
+    "lib": ["es5", "dom", "es2015.collection"]
+  }
+}