Add ISystemUiProxy#toggleQuickSettingsPanel.

This allows other process (such as Launcher variants) to toggle QS from
outside of SystemUI.

This CL also does a couple more things:
- Change #togglePanel to #toggleNotificationsPanel in order to
  distinguish the two #toggleXXPanel calls
- Stop using the depreciated PanelExpansionInteractor#isPanelExpanded
  and use ShadeInteractor#isAnyExpanded instead
- Added Javadocs to some CommandQueue.Callback methods

Bug: 199333223
Test: Call on SystemUiProxy#toggleQuickSettingsPanel from a different
process, see QS expands/collapse.
Flag: None
Change-Id: I477b55f019fcebe5fd10f8f8f1b547d7281172cc

Change-Id: I7d2928b14089289c6b075f2d5a6b9d03677d3b6c