Integrate system feature codegen into SystemConfig

Add initial hooks from SystemConfig to query against system features
that are compiled into the framework via build flags. The behavior
is as follows:

  * System features compiled as available will always be exposed
  * System features compiled as unavailable will never be exposed
  * Runtime parsing of system features won't override compiled features

Currently, we log a warning if there's a conflict between the set of
compiled and runtime system features, but this will likely be elevated
to an exception after additional hardening and development.

The current codegen is a no-op with respect to this behavior, as
RELEASE_USE_SYSTEM_FEATURE_BUILD_FLAGS is flagged as off.

A follow-up change will integrate RoSystemFeature queries into:
  * ApplicationPackageManager - To bypass binder calls when possible
  * SystemServer - For various hasSystemFeature checks

Bug: 203143243
Test: atest FrameworksServicesTests
Flag: build.RELEASE_USE_SYSTEM_FEATURE_BUILD_FLAGS
Change-Id: I1fcd2f2f86dc5605f33182e88fc98a21b57bf812