Block pattern inserter modal: adding a pattern moves focus outside of the Modal

[ciampo]

What

When clicking on a pattern in the block patterns inserter modal, focus is moved outside of the modal itself.

https://github.com/user-attachments/assets/5bcacc13-7562-43e9-8d5e-dc7647e9255e

Not sure if this has always been a problem, or if it's a regression caused by other changes.

Proposed solution

Losing focus while the modal is open is considered an anti-pattern.

There are two alternative solutions:

• Keep the focus on the selected pattern in the modal
• Close the modal when moving focus outside of it

[ciampo]

cc @ntsekouras and @scruffian who are among the last folks to have worked on this

[ntsekouras]

If I remember correctly when it was first implemented the inserter used to close and there was no focus loss issue. This seems related to the changes to keep the inserter open after an insertion. Maybe @MaggieCabrera can ping some folks to see if that's the case?