Not all feature flags should be FCV gated, because FCV is only really usable for features that involve storage changes or inter-node protocol, and that can be locally checked on a mongod (never on a mongos).

Because of this we should add a required feature flag IDL parameter of "shouldBeFCVGated”. If this is false, then the feature flag won’t require a version parameter, so the feature flag will only be gated based on whether it is enabled by default on that binary version.