Move ProcessStateRecord to psc package

The `ProcessStateRecord` class has been moved from the package
`com.android.server.am` to `com.android.server.am.psc` to improve code
organization.

This involved updating imports and references across affected files.
Method visibilities and synchronization annotations were adjusted as
needed.

Bug: 425766486
Test: mmm frameworks/base/services/
Test: atest MockingOomAdjusterTests
Flag: EXEMPT pure refactor

Change-Id: I2bfb5bd584358add21eaef798e36b3552d0ea182