Pattern Inserter: Fix bug where the inserter cannot be closed if the user changes pattern category

[andrewserong]

This PR removes the key from PatternInserterPanel so that the component isn't replaced when the selected category changes.

Description

As a user, if I open the inserter, click to browse patterns, and then change the pattern category, the SelectControl in PatternInserterPanel loses focus. Because the focus is now outside of the inserter, if I click the inserter button or elsewhere within the post, the inserter is not automatically closed, because the focusOutside of the inserter's useDialog.

Screenshot of the bug

Note that after switching pattern category, the select element loses focus and the inserter cannot be closed via the button or clicking on the post body.

Screenshot of the fix

The fix is to remove the key attribute from PatternInserterPanel so that switching pattern category does not cause the whole panel to be replaced, so that the focus is maintained on the select element. This then ensures that clicking the inserter button, or back into the post body, will close the inserter.

How has this been tested?

Manually tested in the editor:

1. Open up the editor (post or page).
2. Click the + icon to open the inserter.
3. Click the Patterns tab.
4. Click the pattern category drop-down and select any other category.
5. Click the + icon to close the inserter, or click into the post body to close the inserter.

Types of changes

Bug fix:

• Remove key from PatternInserterPanel in BlockPatternsTabs so that we don't lose focus when changing pattern categories

Checklist:

• My code is tested. (manually tested)
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation. (not needed for this change)
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. (no React Native files affected as far as I can tell)

CC: @youknowriad and @apeatling as I can see you've both touched files related to this feature recently!

Note: I don't have access to merge, so if this fix looks good, can someone please merge it in for me? Thank you! 🙇‍♂️

[youknowriad]

Thanks for the fix.

[andrewserong]

Thanks for reviewing and merging! 😊