Fix and improve miscellaneous things in Folders tab

[philippotto]

Quoting from #6669

Bugs:

• switching to another orga causes error-toast to appear because folder id from url is loaded
• dragged row has full opacity on some browsers / OS ? makes it hard to see where it's being dropped over. use setDragImage to generate a small drag image so that the wide row doesn't block other elements anymore.
• right sidebar doesn't mention limiting of search results when stating total amount (should do the same as the headline)
• cancelling new-folder input still creates folder
• using context menu on not-selected folder should not select it
• deleting active folder should select another folder

Improvements:

• clearer display of "default" permissions (tag can be confused with actual team)

URL of deployed dev instance (used for testing):

• https://foldersfollowup.webknossos.xyz

Steps to test:

• I tested all of the described things. I think, there's no need to test the time-consuming things again (e.g., orga switching or search result limit). However, the other things, such as dragging a dataset should be easy to test :)

Issues:

• contributes to [Follow-up] Folder Enhancements #6669

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(Please delete unneeded items, merge only when none are left open)

• Updated (unreleased) changelog
• Ready for review

[daniel-wer]

Very nice, everything works as described, LGTM 👍

Great improvement for the drag preview, in particular!