Add gRPC Transport support (#356)

Co-authored-by: JimhHan <50871214+JimhHan@users.noreply.github.com>

transport/internet/grpc/errors.generated.go

@@ -0,0 +1,9 @@
+package grpc
+
+import "github.com/xtls/xray-core/common/errors"
+
+type errPathObjHolder struct{}
+
+func newError(values ...interface{}) *errors.Error {
+	return errors.New(values...).WithPathObj(errPathObjHolder{})
+}