[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/go/greeter/README.md

@@ -0,0 +1,25 @@
+# Go Greeter example
+
+## Project Structure
+
+    .
+    ├── server                   # Server module
+    ├── client                   # Client module
+    ├── models                   # Flatbuffers models & main grpc code.
+    └── README.md
+
+## How to run Server:
+
+- `cd server`
+
+- `go clean`
+
+- `go run main.go`
+
+## How to run Client:
+
+- `cd client`
+
+- `go clean`
+
+- `go run main.go --name NAME`