Add batchSetOomAdj()

Integrating PROCS_PRIO cmd, from LMKD, to allow batching of oom
adjustment of processes.

Test: Verified LMKD processes the batching PROCS_PRIO request
Test: Verified that we can enable batching oom adj flag
Test: m
Bug: 325525024
Change-Id: I02dbdf60b4d34b765949df1787df7b817fe39dbf
Signed-off-by: Carlos Galo <carlosgalo@google.com>