[Go] Working on a go example plus fixing go grpc code (#6448)

Implemented server.go and half implemented client.go

Finishes implementation for greeter go example

Update grpc code for monster.fbs

Adds a couple of cpp methods

Adhere to gofmt standards

Adds a readme for issues with grpc

grpc/examples/greeter.fbs

@@ -0,0 +1,14 @@
+namespace models;
+
+table HelloReply {
+  message:string;
+}
+
+table HelloRequest {
+  name:string;
+}
+
+rpc_service Greeter {
+  SayHello(HelloRequest):HelloReply;
+  SayManyHellos(HelloRequest):HelloReply (streaming: "server");
+}