big refactor. make compatible v2 and v1 interface

custom/grpc_interface.go

@@ -0,0 +1,10 @@
+package main
+
+import "C"
+import v2 "github.com/hiddify/libcore/v2"
+
+//export StartCoreGrpcServer
+func StartCoreGrpcServer(listenAddress *C.char) (CErr *C.char) {
+	err := v2.StartCoreGrpcServer(C.GoString(listenAddress))
+	return emptyOrErrorC(err)
+}