Enable copy/cut shortcut on the site editor

[t-hamano]

What problem does this address?

I was testing shortcuts on Windows in #43352 and found that the copy/cut shortcut doesn't work only in the site editor.
This does not seem to be an OS issue.

Personally, I feel it is very inconvenient that this shortcut is not available in the site editor.

What is your proposed solution?

Unless there is a clear reason not to opt-in to this shortcut in the site editor only, I believe the shortcut should be added like any other editor.

As a test, I merged the useClipboardHandler into the following ref, and the shortcuts seem to work on the site editor:

gutenberg/packages/edit-site/src/components/block-editor/index.js

Line 122 in 1d778aa

const mergedRefs = useMergeRefs( [ contentRef, useTypingObserver() ] );

Screencast

4b05473e82d30aedd7a0f447033c2dc4.mp4

[noisysocks]

Hi @t-hamano I unassigned you as I can't see that you're working on this. Re-assign yourself if I'm mistaken 😀

[t-hamano]

@noisysocks
Sorry, I forgot to address this issue. I hope to submit a PR soon.