Log warnings for slow input event interceptions.

InputDispatcher is mostly self-contained, but reaches out to the rest of
the world when it checks to see if an event needs to be intercepted. We
should make sure these interceptions stay fast as it blocks the whole
input system when they aren't. Worse, if the reason we're slow is that
we've called into an ANRing part of the system, we won't actually be
able to trigger the ANR and dump stacks until after its already
recovered.

Also, apply constexpr to a few more constants.

Bug: 72113907
Test: build, flash, see it complain if I make it artificially slow
Change-Id: Iff4a4fbeda963a00538720eebdb3fd5bd81f9875