Fix nodes being deselected upon reparenting

[aXu-AP]

Fixes inconsistency when moving nodes in hierarchy, as reparenting caused nodes to be deselected (vs reordering children of same node).
This especially improves flow when building a skeleton by duplicating and reparenting bones:

There isn't existing issue about this, just a short conversation at rocket chat.

[KoBeWi]

Reparenting resets the inspector, unlike normal moving:

godot.windows.editor.dev.x86_64_riQ3FfGvqP.mp4

Though not sure if it can be reasonably solved.

[aXu-AP]

Thanks for noticing. I made it so that nodes get reselected so that inspector opens as well. This has the caveat that if something else was opened in the inspector then changing the object wouldn't be desired, but it's much rarer case than having selected nodes opened.

[KoBeWi]

Your last change did not address my comment.
Notice how I had everything unfolded in the inspector and it was scrolled, but after moving, everything is folded again, with scroll reset to 0. It does not happen with single node though.

If you can't solve it then it's fine too I guess, still better than how it was before. But then you should probably revert your last change, as it doesn't really serve purpose.

[aXu-AP]

Oh, you're right. To be exact, the problem occurs only when reparenting multiple nodes. Single node retains its unfolded sections. I must have tested it on a single node and thought that the problem got solved.
Tbh the logic for remembering unfolded sections could be better overall.

[akien-mga]

Thanks!