update synth.is_realizable to new synthesize signature
update synth.is_realizable to new synthesize signature

which accepts env and ignore_env_init

tulip-control/tulip-control,tulip-control/tulip-control,necozay/tulip-control,necozay/tulip-control,necozay/tulip-control,necozay/tulip-control,tulip-control/tulip-control,necozay/tulip-control,tulip-control/tulip-control