Proposal: Add snackbar notification when unlocking content only blocks

[richtabor]

Perhaps there is a persistent snackbar that renders when you opt to unlock a content-only locked block.

This would allow you to easily re-lock a temporarily unlocked block, instead of having to find the "Done" control on the parent locked block. I'd expect that selecting "Done" in the block toolbar of the parent block would dismiss the snackbar, and clicking the "Lock" call the action would re-lock the block and dismiss the snackbar.

Perhaps the copy needs refinement, but I think it's an interesting approach to be able to easily re-lock a recently unlocked content-only block.

I thought of this while reviewing https://github.com/WordPress/gutenberg/pull/61127.