[TASK] Clean up SvgTree code

Now that jQuery has gone and TypeScript is in place for Tree components,
the next step is to consolidate and sort out re-usability.

This change prepares the way for allowing multiple trees in the
navigation component area (for FileStorageTree).

* ContextMenu allows int+number (which is correct)
* ContextMenu has all information from the TreeNode (and not the SVG
  element) - less Markup!
* KeyTypeEnums are used throughout SvgTree
* Centralized place for error notifications, removing duplicate code
* tree.settings.isDragAnDrop is removed in favor of
  tree.settings.allowDragMove (which already exists)
* Unused properties in TreeNode are removed
* Since we are now in "TS module land", PageTreeToolbar.ts is removed
  because the class is only used in the PageTreeElement, so it does
  not need to be exposed anymore.

Resolves: #93481
Releases: master
Change-Id: Ia9bff532132dba5aea85352d7e510f6a7f9459c6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67683
Tested-by:...