Do not enable changes newer than the current sdk

Do not allow enabling compat changes in APEX gated on an sdk version
greater than the current one.

Test: atest OverrideValidatorImplTest
Test: atest PlatformCompatTest
Bug: 175790344
Bug: 179149558
Change-Id: Idd7d86f96a380bfe01940f356d38ad49d3f27678
10 files changed