Fix GraphEdit layering

[Geometror]

trafficstars

This PR fixes/improves the ordering of comment nodes as children of GraphEdit as well as the position of the connections layer. Split from #61414.

Detailed changes:

• the order of comment nodes is now calculated similar to a 2D BVH: when a comment node encloses other comment nodes, the index of the enclosing node is kept below
  • the order is updated when resizing a comment node
• the connections layer is now kept between the comment nodes and the normal graph (due to technical limitations it is no longer an internal node)

Before:

This PR:

[fire]

The nesting in GraphEdit::_top_layer_input is very deep. will review more.

[reduz]

This looks good to me, what is it missing?

[akien-mga]

This looks good to me, what is it missing?

Mostly a contributor that feels confident enough with GraphEdit to approve the feature and implementation :)

[fire]

I'll take a look. Can it be rebased and ready to merge?

[Geometror]

@fire Rebased. Just for reference: For now(4.0) I think this will do, but since it is a bit hacky I would like to refactor the current GraphNode/GraphEdit system including the restructuring(#61414) and implementation of layers (or something similar) in the next few months after I opened a proper proposal. A problem might be compatibility breakage so that needs to be discussed.

[fire]

There's some conflicts.

[YuriSizov]

So, from some quick testing this doesn't seem to work completely as expected. For a new shader the comments are still in front of the connections:

But closing and reopening the file fixes it, even for the nodes added afterwards:

Am I doing something wrong?

[akien-mga]

Superseded by #67152.