ANDROID: introduce a vendor hook to allow speculative swap pagefaults

Since SPF is an out-of-tree feature, the risks of changing its behavior
are higher. Add a vendor hook to enable speculative swap pagefaults. By
default it's disabled and should not cause troubles for current users.

Bug: 322762567
Change-Id: I3df7c545aa27d2707ee51ea42368f785c5faa735
Signed-off-by: Suren Baghdasaryan <surenb@google.com>