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.

tslint.json

@@ -0,0 +1,8 @@
+{
+  "extends": "@microsoft/sp-tslint-rules/base-tslint.json",
+  "rules": {
+    "class-name": false, "export-name": false, "member-access": true,
+    "no-console": false, "no-duplicate-variable": true, "no-shadowed-variable": true,
+    "semicolon": true, "typedef": false, "variable-name": false, "whitespace": false
+  }
+}