entgrpc: support separate package - #579

package foo
type UserService struct {
	client *ent.Client
	UnimplementedUserServiceServer
}

WS_ROOT="/workspace/foo"
PROTO_ROOT="${WS_ROOT}/proto"
MODULE_NAME="example.com/foo"
protoc \
	-I="${PROTO_ROOT}" \
	--go_out="${WS_ROOT}" \
	--go_opt=module="${MODULE_NAME}" \
	--go-grpc_out="${WS_ROOT}" \
	--go-grpc_opt=module="${MODULE_NAME}" \
	--entgrpc_out="${WS_ROOT}/bar" \
	--entgrpc_opt=module="${MODULE_NAME}" \
	--entgrpc_opt=package="${MODULE_NAME}/bar" \
	--entgrpc_opt=schema_path="${WS_ROOT}/schema" \
	--entgrpc_opt=entity_package="${MODULE_NAME}/ent" \
	foo/user.proto

package bar
type UserService struct {
	client *ent.Client
	foo.UnimplementedUserServiceServer
}