Make PiP move away to not occlude IME when it's too big

Keep clear algorithm don't change position if there is no space, but in
corner case scenario if the insets simply weren't big enough to even
contain PiP height, it would lead to occluding IME.

With this change we are now moving PiP when it doesn't fit in the insets
to be positioned according to the gravity rules, even if user has
interacted with it, which also brings PiP down when IME hides.

Bug: 283172848
Test: http://recall/-/g8x7ZkgdfbqscttAA9wzl9/4Qxus5Q16e4SyHtJPgdtS

Change-Id: Ia4c797ef484bc917cf1579ab2f0f72cfd4646169