Define policy for /proc/uid_io/stats

New procfs file read by storaged to dump fg/bg IO usage.

Remove kmsg rule since it's no longer used by storaged.

Allow storaged to find permission_service to translate UID
to package name.

Test: adb shell storaged -u
Bug: 34198239
Change-Id: I74654662c75571cbe166cf2b8cbab84828218cbd