Migrate table cell dropdown to a bubble menu

What does this MR do and why?

Migrate table cell dropdown to a bubble menu

Changelog: added

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• Insert table not usable in work item drawer (#521064 - closed)
• Table cell context menu not usable inside a drawer

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

I made the "bubble menu" behave exactly like it was before. Should work properly in a drawer now. UX wise there is no change from before.

Screen Recording 2025-02-28 at 18.18.13.mov

This also fixes a strange bug from before where you'd see dropdowns in several rows:

We now show a dropdown only in the selected cell, or in case you're selecting multiple cells, we show it on the top right corner of the union rectangle of the selected cells.

How to set up and validate locally

1. Enable ff work_items_view_preference and turn on "New issue look"
2. Go to an epic, click any of the child items to open it in the drawer.
3. In the opened issue in the drawer, go to the text box
4. In the text box, switch to rich text editing
5. Insert table (in the main formatting menu) should work as expected.
6. Insert a new table.
7. Select one or more cells.
8. The table cell operations should work as before.

Related to #521064 (closed)