fix: focus after drag and deleting comments

[maribethb]

The basics

• I validated my changes

The details

Resolves

Fixes #8825

Proposed Changes

• has RenderedWorkspaceComment declare that it implements IFocusableNode, it already did this so idk why it didn't say it did
• adds a timeout when focusing the workspace after disposing a block. the reason this is needed is in case of deleting a block via dragging it to the workspace, we need to wait for the timeout otherwise when focusing the workspace, the block we're about to delete is still focused
• focuses the workspace when a comment is deleted

Reason for Changes

Test Coverage

There are tests for this in keyboard-nav which I'll update when I remove the extra delete handling code there. It's a whole can of worms to move those tests into core, so for now, they'll live in keyboard-nav but will move into core with many of the other keyboard nav tests post-launch

Documentation

Additional Information