Add handle menu to bar type window caption.

Adds a menu on clicking handle that will enable windowing changes. Still
to implement for this prototype: More button, Split Screen button,
Overtop/Float button.

Bug: 239960071
Test: Launch various tasks, confirm handle menu appears, drag
functionality is unaffected.

Change-Id: I0aeeffb44e6bfd580c70270e562d8c04031892de