psc: Add ProcessProviderRecordInternal

This change introduces ProcessProviderRecordInternal to serve
as an internal abstraction for OomAdjuster's access to content
provider data.

Now some of OomAdjusterImpl's methods use ProcessProviderRecordInternal,
decoupling from the concrete ProcessProviderRecord implementation.

Bug: 425766486
Test: m services.core
Test: atest MockingOomAdjusterTests OomAdjusterTests
Test: atest FrameworksServicesTestsRavenwood_ProcessStateController
Flag: EXEMPT pure refactor

Change-Id: I313288c0b4a4fe2722ecb530a1317011eaa32dba