feat: Enhance MegaMenu with localization, caching, and new properties

- Added localization support for loading states, empty navigation, and submenu actions in both German and English.
- Introduced new properties in IMenuItem for description, openInNewWindow, and external links.
- Updated SPTermStorePickerService to handle cache versioning and language-specific caching.
- Implemented a new MegaMenuCore service for handling term properties, cache management, and navigation URL resolution.
- Refactored TaxonomyNavigationService to build menu hierarchy and filter hidden terms.
- Added automated tests for MegaMenu core functionalities and static asset validation.
- Removed unused ItemDictionary service.
- Created a comprehensive ToDo document outlining the implementation status and future tasks.

src/services/ISPTermStorePickerService.ts

@@ -78,11 +78,22 @@ export interface ITerm {
   PathDepth?: number;
   ParentId?: string;
   TermsCount?: number;
+  Labels?: ITermLabelCollection;
   LocalCustomProperties?: {
     [property: string]: any
   };
 }
 
+export interface ITermLabelCollection {
+  _Child_Items_: ITermLabel[];
+}
+
+export interface ITermLabel {
+  Language: number;
+  Value: string;
+  IsDefaultForLanguage?: boolean;
+}
+
 export interface ISuggestTerm {
   Id: string;
   DefaultLabel: string;