Working on a python example plus fixing python grpc code (#6456)

Refactored python grpc code gen

Adds example server & client + fixes ci

Fixes generated code

Making sure we encode the reply string as utf8

Adds Readme details to clarify issue regarding encoding when python is sending/receiving

grpc/examples/python/greeter/README.md

@@ -0,0 +1,12 @@
+# Python Greeter example
+
+## Prerequisite
+
+- You need to have grpc python installed on your device `pip install grpcio`
+## How to run Server:
+
+- `python server.py ${PORT}`
+
+## How to run Client:
+
+- `python client.py ${PORT} ${NAME}`