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Description

When calling KeyboardNavigation.dispose() and then creating a new KeyboardNavigation instance, a crash occurs due to a collision in keyboard shortcut registration, specifically for the "undo" and "redo" actions.
Blockly throws an error for trying to register keyboard shortcuts that already exist:

Uncaught (in promise) Error: Shortcut named "undo" collides with shortcuts "undo,undo"

UndoRedoAction backs up the original shortcuts before registering the new ones, but it doesn't actually unregister the old ones first. The root of the issue is that UndoRedoAction.uninstall() attempts to re-register the original shortcuts, but those don’t have allowCollision, causing registration to fail. Note that there are two 'undo' shortcuts in the error shown above because plugin only installs a new shortcut. Creating the instance should unregister the original shortcuts. Disposing of a KeyboardNavigation instance should also unregister all shortcuts cleanly.

I suggest updating UndoRedoAction to explicitly unregister the undo/redo shortcuts before registering the keyboard navigation versions and before restoring the original ones.

In the meantime, we can workaround this locally by unregister undo and redo from the ShortcutRegistry. We have to do this before creating the instance (to remove the originals) and before disposing (to remove the plugin shortcuts).

Reproduction steps

1. Create an instance of KeyboardNavigation.
2. Call .dispose() on that instance.
3. Create a second instance of KeyboardNavigation.

Stack trace

addKeyMapping	@	shortcut_registry.ts:117
register	@	shortcut_registry.ts:64
uninstall	@	undo_redo.ts:70
dispose	@	navigation_controller.ts:276
dispose	@	index.ts:138

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