ToolsPanel: Prevent calling deselect when panel remounts

[aaronrobertshaw]

Fixes: #43491

What?

Prevents controls within a ToolsPanel from erroneously calling their onDeselect callback and resetting the control's related block attribute when the ToolsPanel gets remounted, e.g. when a block is dropped in a new location.

Why?

Losing customizations you've made is bad.

How?

If the ToolsPanel has been remounted, its internal state for menu items will also be reset. Items added to the panel via SlotFill will persist while the panel gets remounted. This leads to their derived state being out of sync with the context value provided by the panel. This PR checks whether the item is currently registered with the panel and, if it isn't, skips any calls to onSelect or onDeselect callbacks.

Testing Instructions

1. Before checking out this PR, edit a post, add multiple paragraph blocks, and move one paragraph into a group block.
2. Select the paragraph within the group block and apply custom typography styles for all typography options
3. Save the post
4. Drag the paragraph block to a new position outside of the group and notice that several typography customizations are lost e.g. Font family.
5. Checkout this PR and reload the editor
6. Drag the paragraph block out of the group block again and note that all typography customizations are maintained

Screenshots or screencast

Screen.Recording.2022-11-09.at.3.52.09.pm.mp4

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[dsas]

This tests nicely for me 👍

[andrewserong]

Nice one, thanks for fixing this up @aaronrobertshaw!

✅ Confirmed the issue on trunk
✅ With this PR applied, moving a paragraph block with all typography settings in use out of a Group block and to elsewhere in the document now preserves all the settings in use

LGTM! ✨