Flag to allow notifs with shortcuts to have BubbleMetadata

- Add shortcut option to experiment class
- Attempts to create BubbleMetadata off of ShortcutInfo, unfortunately
  it doesn't really have a lot of info about the shortcut.... so using
  an intent extra to note that
- Adds new API to ActivityView to support launching shortcuts

Test: manual - enable flags, post a notification with valid shortcut info,
               longpress on it to bubble, tap on bubble
Bug: 143173197
Bug: 138116133
Change-Id: Id631bf4a4b97e0bb1f76760f48dbfc11ffc0630e