This commit also changes the U shortcut to open the unwrap menu instead
of the Unwrap operator. The unwrap operator can now be accessed by
pressing U twice.
Note, these operators use the 3D Viewports selection and not the UV
Editor selection. In the future the operators should unwrap based on the
selection within that editor.
Fixes T80600
Differential Revision: https://developer.blender.org/D8834
4e3cb95638