Added handling for shortcuts and pending intents.

Updated BubbleController to support shortcuts and pending intents.

Test: atest BubbleControllerTest
Test: Manual. Have a shortcut and app icons in the taskbar.
Drag and drop both items over the bubble drop zone.
Observe that items are added to the bubble bar.
Video: http://recall/-/gx8ASgewUeUS3QYohfrd1J/fnHDKrNWzJEzRw6rgIm0fG
Flag: com.android.wm.shell.enable_create_any_bubble
Bug: 388894910

Change-Id: I0b050bea64df89f0999ac27622cac5a353f28be3