Implement device idle in power manager.

When in device idle mode, we now prevent most apps
from being able to hold partial wake locks.  The
device idle controller now pushes its white list of
app uids into the power manager, so it can apply this
policy correctly to only apps that are not whitelisted.

The implementation adds a new "disabled" flag to a wake
lock which is set when we want to apply this policy.  When
set, we ensure that we tell battery stats that the wake lock
is not being held and ignore that wake lock when computing
the power state summary.

Also add new SDK APIs to schedule alarms that are allowed
to execute while in idle mode.

Finally add new dumpsys commands to the device idle controller
to completely disable and re-enable its operation, to use
for testing.

Change-Id: I1f16672c6ac06d03bb538f9854d5843db9aa6f27