Fix copy-buttons in context menu and change out-of-context-menu-click behavior

[philippotto]

With this PR:

• the copy buttons in the context menu are fixed (before the PR, the blur() event was triggered directly and the menu was closed immediately)
• clicking outside of the context menu closes it (and doesn't do anything else, such as creating a node)
• the only downside: a repeated rightclick doesn't open the context menu again. technically, this should be possible, but the effort to implement this is several times higher than the current pr. Also, I think, it's not that important (right now, at least).

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

• open a tracing (disable classic mode)
• open a context menu via right click
• use the copy buttons (e.g., copy position) and ensure that the position is copied.
• the context menu will stay open (I find that okay)
• left click outside of the context menu --> the menu should close, but no node or similar should be created
• right click outside of the context menu --> the menu should close and nothing else will happen. ideally, the context menu would open again, but as explained above, this "feature" got dropped with this PR for now.

Issues:

• fixes Disable viewport click interactions while context menu is open #5606
• fixes copy from contextmenu doesn't work: can't copy segment-id or position #5657

---

• Updated (unreleased) changelog
• Updated (unreleased) migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Needs datastore update after deployment
• Ready for review

[MichaelBuessemeyer]

Works very well :)