Align home/back button from overview with tap outside

Set all interpolators in QuickstepAtomicAnimationFactory instead of
overriding some in OverviewToHomeAnim. This also means we can just
use a normal state transition instead of OverviewToHomeAnim when
tapping outside recents (i.e. startHome()).

Test: in all three gesture modes, the same animation is played
whether tapping outside recents, pressing home, or pressing back
Bug: 185411781

Change-Id: Ibe8734e8bd7041943eb76cac30d7cac26a90c73e