Delete widgets that have been removed from all sidebars.

[TimothyBJacobs]

Description

After the widget areas have been saved, delete any widgets that had their blocks removed.

How has this been tested?

Manually tested.

Types of changes

Bug fix.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[draganescu]

I wonder what is the role of inactive widgets area (see #26232) if we merge this behavior?

[TimothyBJacobs]

I think that's a valid product question to explore. But in the current widgets area, deleting a widget deletes the widget, it doesn't move it to the inactive widgets area. That happens if the widget is moved there manually, or if the widgets can't be moved automatically by retrieve_widgets when the theme changes. The intent of this PR was to restore that behavior IIRC.

[kevin940726]

This needs a rebase since we don't rely on clientId anymore. See #28379 and #29111.

[draganescu]

Yes, after rebase, given the news from @kevin940726 the PR needs a rewrite :(

[TimothyBJacobs]

👍 I don't have too much time this cycle, so I'll go ahead and close this out.