Create BubbleBarCaptionView to hold the handle view.

This will make it so that a Bubble's caption view will be opaque and drawn on top of the insetted TaskView. The caption view color will match the task background color if there is one.

Demo: http://screencast/cast/NDk1NTM4MTgwODc1ODc4NHxmYWFkMTE5Zi1kMg
Fix: 416047465
Bug: 403612933
Test: wm presubmit
Flag: com.android.wm.shell.enable_create_any_bubble
Change-Id: Iaea092947d1a1acc3a36acff26baf7a209fde1ad