dump psi stat into bugreport

PSI gives good insight for cpu,memory and IO subsystem trobule
for last 10s, 60s and 5m in the system. It would be very helpful
to detect/prove system issues.

Bug: 141884936
Test: adb bugreport and check bugreport file includes PSI metric
Change-Id: I88fec350d5e62e9a2176f2c9363a35d41e41f14c
Signed-off-by: Minchan Kim <minchan@google.com>