1/N Add QSFragmentComponent

This introduces the QSFragmentComponent as a way to create
QS related view controllers. The QSPanelController is introduced, but
doesn't do much other than proxy through most QSPanel calls.

Bug: 168904199
Test: manual && atest SystemUITests
Change-Id: I1fccda95f38722bf0215b2f15f65cd70ec66283a