SERVER-99351 incorporated Operation FCV into the FCV-gated Feature Flag API. This requires calling VersionContext::getOperationFCV() from within FCVGatedFeatureFlag::isEnabled(...).

Since feature flag checks are run from many places and thus are relevant from performance, we should ensure that the generated code for VersionContext::getOperationFCV() is well-optimized and that it gets inlined into a simple instruction sequence into FCVGatedFeatureFlag::isEnabled(...).