Adds a `text` parameter to `bpy.types.uiLayout.template_ID()` which
causes a label to be added, as usual. Adding the label also makes the
template respect the `bpy.types.uiLayout.use_property_split` option.
Also fixes wrong layout being used in the template-ID, although I think
that didn't cause issues in practice.
Sergey requested this for usage in the Movie Clip Editor.
5bcb0c9935