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.

classic/classic-deployment.md

@@ -19,6 +19,7 @@ Die Classic-Variante liest die `ClientSideComponentProperties` der zentralen Meg
   "termSetId": "7948e6f9-7af4-431e-b6fe-328122f2746c",
   "termSetName": "Global Navigation",
   "cacheMinutes": 15,
+  "cacheVersion": "1",
   "menuMode": "megaMenu",
   "debug": false
 }
@@ -26,6 +27,8 @@ Die Classic-Variante liest die `ClientSideComponentProperties` der zentralen Meg
 
 `menuMode` erlaubt `megaMenu` oder `flyout`. `termSetId` hat Vorrang vor `termSetName`.
 
+Die lokalen benutzerdefinierten Term-Eigenschaften `MegaMenu.Hidden`, `MegaMenu.OpenInNewWindow` und `MegaMenu.Description` werden wie in der modernen Variante ausgewertet. Der Cache ist nach Site Collection, Sprache und `cacheVersion` getrennt.
+
 ## Einbindung
 
 Die drei Dateien beispielsweise nach `/SiteAssets/megamenu/` hochladen und in dieser Reihenfolge laden: