Move broadcast receiver for showing security dialog

Move the logic completely into QSSecurityFooter, so we don't need to
keep track on where it's attached.

Also, start removing NEW_FOOTER flag uses

Bug: 220344583
Test: atest SystemUITests
Test: manual
Change-Id: Ibbf0212311ecd3afd512131a9b0960a4cbacceb7
5 files changed