Remove shortcuts that no longer exist or are no longer pinned.

Remove shortcuts that no longer exist or are no longer pinned.

(This change is in the onShortcutsChanged() callback.)

- Remove all workspace icons that correspond to shortcuts that
  are now unpinned
- Remove all workspace icons that have the same package and
  user handle as passed in onShortcutsChanged(), if they aren't
  included in the list of shortcuts that is also passed.

These cases will happen for static and dynamic shortcuts,
respectively, when an app's data is cleared.

Bug: 30316501
Change-Id: I50db6567cb318d087012ab5d8208e765b81c6f99