Copy/Paste property paths/values in inspector.

Resolves godotengine/godot-proposals#106.

Adds the following property menu options with default bindings:

- Copy Property (ctrl+c)
- Paste Property (ctrl+v)
- Copy Property Path (ctrl+shift+c)

If you hover over a property label in the inspector dock, you can copy
either the property value or the property path to the system clipboard
using the shortcuts above This is especially useful for the
`AnimationTree`, where code might reference properties like
"parameters/state/aim/move/blend_position".

One issue is that if you click a property, then click on the node you
currently have selected in the node tree, then press ctrl+shift+c, it
will still copy the selected property path rather than the node path. If
you click on a different node in the nodetree, however, ctrl+shift+c
will return to copying the nodepath.

The property value copy/paste was implemented by @KoBeWi at #39398 and
merged into this PR due to their similarity.

0 files changed, 0 insertions, 0 deletions