ANDROID: Sched: Add restricted vendor hooks for scheduler

Adding vendor hooks in several areas of the scheduler code.
These are needed for implementing Qualcomm's load tracking scheme WALT
via vendor modules. Due to WALT's proprietary nature, these changes
cannot go upstream.

This commit reverts commit dafc604d ("Revert "Revert "Revert
"ANDROID: Sched: Add restricted vendor hooks for scheduler"""").
It was originally reverted multiple times to facilitate upstream merges.
Effectively, bringing back the original change.

Bug: 200103201
Bug: 243793188
Change-Id: Ib340c03ddccd4218cac1cca382a2c6e93064de02
Signed-off-by: Ashay Jaiswal <quic_ashayj@quicinc.com>
Signed-off-by: Sai Harshini Nimmala <quic_snimmala@quicinc.com>