am: Make forEachConnectionLSP use internal classes

This change refactors the OomAdjusterImpl.forEachConnectionLSP() and its
related methods to internal record classes for improved encapsulation
and design.

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

Change-Id: Idb423b88beaea70a4fb60cc2f6fde08bcd827934