feat: Support for multiple rpc service generation and rpc grouping (#1972)

* Add group & compatible flag

* Add group & compatible flag

* Support for multiple rpc service generation and rpc grouping

* Support for multiple rpc service generation and rpc grouping

* Format code

* Format code

* Add comments

* Fix unit test

* Refactor function name

* Add example & Update grpc readme

* go mod tidy

* update mod

* update mod

tools/goctl/example/rpc/hello/hello.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/zeromicro/go-zero/tools/goctl/example/rpc/hello/internal/config"
+	greetServer "github.com/zeromicro/go-zero/tools/goctl/example/rpc/hello/internal/server/greet"
+	"github.com/zeromicro/go-zero/tools/goctl/example/rpc/hello/internal/svc"
+	"github.com/zeromicro/go-zero/tools/goctl/example/rpc/hello/pb/hello"
+
+	"github.com/zeromicro/go-zero/core/conf"
+	"github.com/zeromicro/go-zero/core/service"
+	"github.com/zeromicro/go-zero/zrpc"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/reflection"
+)
+
+var configFile = flag.String("f", "etc/hello.yaml", "the config file")
+
+func main() {
+	flag.Parse()
+
+	var c config.Config
+	conf.MustLoad(*configFile, &c)
+	ctx := svc.NewServiceContext(c)
+
+	s := zrpc.MustNewServer(c.RpcServerConf, func(grpcServer *grpc.Server) {
+		hello.RegisterGreetServer(grpcServer, greetServer.NewGreetServer(ctx))
+
+		if c.Mode == service.DevMode || c.Mode == service.TestMode {
+			reflection.Register(grpcServer)
+		}
+	})
+	defer s.Stop()
+
+	fmt.Printf("Starting rpc server at %s...\n", c.ListenOn)
+	s.Start()
+}