ANDROID: power: add a vendor hook to log unfrozen tasks

We recently noticed an issue where freezing of user space tasks
is failed due to a process being in uninterruptible sleep state.
Currently, the logging of unfrozen tasks is disabled by default.
Although it can be enabled for debugging via a adb command, it's
usually hard to reproduce the issue. So we want to add a vendor
hook to log unfrozen tasks.

Bug: 240091483
Test: all presubmit tests passed
Change-Id: Ief3d4196ea7220d4897c00a37ab96f456dbf2259
Signed-off-by: Darren Hsu <darrenhsu@google.com>