Customize widgets: Undo and Redo buttons are disabled thus breaking expected keyboard interaction

[afercia]

Description

See #57647

I'm not sure what the plans are for the customize-widgets package so I'm not sure it is worth fixing it. However, the NavigableToolbar with Undo and Redo buttons suffers from the same bugs reported in #57647.

• The buttons used disabled while they should use aria-disabled instead.
• As such, arrows key navigation doesn't work when these buttons are disabled.
• Focus style is not visible.

Screenshot:

Step-by-step reproduction instructions

Basically, repeat the steps from #57647 but test the Customizer instead.

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes