Add DrawingHandle: an app handle that draws itself instead of drawable.

In order to fulfill the handle -> menu open/close spec, the handle must
be animated in such a way that it looks like it is growing into the
windowing pill. In order to do so we have to directly draw the app
handle and "grow" its height and width at a non-scaled rate, and even
increasing its corner radius.

This introduces a new type of app handle behind a flag, borrowing much
of the animation implementation from Bubbles.

Bug: 314288540
Test: Manual. Open/Close handle menu.
Flag: com.android.window.flags.enable_drawing_app_handle
Change-Id: Ia67707f82e4900aa22cde0200b363b428ced36f7