Fix: empty folder's disappearing when copying

[Tiger3018]

TODO:

• portfolio_message omit copy event of the empty folder

Related: #1452, #1633

[Tiger3018]

Notes:

For folder layers, DocumentNode.inputs seems to be [Child_node/Value, Sibling_node]. It's not well documented yet.

[0HyperCube]

That is correct in the current main branch @Tiger3018, however @Keavon is currently reversing the ordering of those inputs (I'm unsure why) in a branch in someone's fork. For documentation on what the inputs are, you can look at the implementation (here the ConstructLayerNode struct) and also the document_node_types.rs file has a string name for the inputs to a node.

[Tiger3018]

For highlighting and group issues, it only appeared in Just a Potted Cactus and Valley of Spires example files. New document and two other example files didn't affected. Maybe a document version issue?

Mark this PR ready for review.

[Keavon]

!build

[github-actions]

📦 Build Complete for 30366ba
https://2696d198.graphite.pages.dev

[Tiger3018]

This PR is not related to discovered issues formerly, and can be merged

[Keavon]

I'm sorry, I actually still can't figure out what this PR addresses. What was the original issue or todo item? Can you please edit the PR description to mention only that?

[Tiger3018]

@Keavon I have removed the portfolio_message to clarifying just the phenomenon in the PR title, and have removed the mention of new issue in the description.

[Keavon]

I'm still not sure precisely what this PR is about but I think it's already solved by the changes made in #1712 so I will close this as it's redundant.