Create BinderLatencyObserver to collect binder call latency stats.

Pushing these as a metric will come in a future change.

This is a direct cherrypick with no changes.

Test: unit tests

Change-Id: I8a123f7aed7c0ce416814372f2287b04a8a04ac0
Merged-In: I8a123f7aed7c0ce416814372f2287b04a8a04ac0
(cherry picked from commit 8d0ecde2)