Add default isPolicyApplied in ResolutionMechanism

This is a method providing a default implementation that simply checks
if the values are equal.

Bug: 285532044

Test: atest com.android.server.devicePolicy.ResolutionMechanismTest#isPolicyApplied_defaultImplementation_sameValues_returnsTrue

Test: atest com.android.server.devicePolicy.ResolutionMechanismTest#isPolicyApplied_defaultImplementation_differentValues_returnsFalse

Flag: TEST_ONLY

Change-Id: I9f7efa1df100e0935c8b36c35a405cc1dedfff22