Previously, menu sockets were always drawn as dropdown. This patch adds the
ability to draw them expanded instead.
As before, in the node editor, only the expanded menu is drawn, without the
label. There is simply not enough space for both. However, in the modifier and
operator settings the label is drawn currently. We'll probably need to add a
separate `Hide Label` option (similar to `Hide Value`) for group inputs that
support it. That would also help a lot with e.g. object sockets.
Pull Request: https://projects.blender.org/blender/blender/pulls/138387
8a42e2b59a