system suspend: more information about wake locks

system suspend: more information about wake locks

/sys/power/{wake_lock wake_unlock} can give a list of all currently
active and inactive wake lock names. Bring system suspend debug
functionality up to par by keeping track of all used wake lock names,
client pids, current state and last used timestamp.

To prevent collected stats from growing unboundedly we evict least
recently used stats entry after a given threshold.

Bug: 78888165
Test: SystemSuspendV1_0UnitTest
Change-Id: I26eb94e61d4656ec1bba45b4a70a0715fae15d05