fix: Allows copying from unsaved content

[nikcio]

Prerequisites

• I have added steps to test this contribution in the description below

If there's an existing issue for this PR then this fixes #14459

Description

This adds a check to the clipboard service that will check if we're copying from an unsaved content node. When we do this we will allow multiple copies based on the display name instead of the unique key. This allows the user to copy multiple lists of blocks from an unsaved content node.

I choose the display name because it's created after the property name and content node name. It will also give a confusing user experience if you could have multiple elements in the clipboard with the same display name.

See the #14459 reproduction section to see how to test the PR 😄

[github-actions]

Hi there @nikcio, thank you for this contribution! 👍

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[georgebid]

Thank you for raising and fixing this one @nikcio 🥳 Someone on the core collaborators team will review this soon!

[georgebid]

I've tested this, and compared it with the before and after (thanks a lot for your details steps in the issue!) and I can see that copying is now working for unsaved entries. Therefore I have merged this in 🎉 Thanks again @nikcio

[nikcio]

Great! Will this also be added to a V8 release and is there any way to know which one? @georgebid

[georgebid]

All contributions go to the contrib branch, and we'll cherry-pick things that make sense to other versions. When the next release happens I believe @nul800sebastiaan will add a comment to note where this has been cherry-picked to 😄 @nikcio

[nul800sebastiaan]

Cherry picked for v10/11 in 30ec9d9

[nikcio]

Hey @nul800sebastiaan
Is there any chance this could get cherry picked for v8?