remove unused protos and cleanup unused code

[shawaj]

From https://github.com/NebraLtd/hm-pyhelper/blob/master/hm_pyhelper/gateway_grpc/client.py

and from https://github.com/NebraLtd/hm-pyhelper/tree/master/hm_pyhelper/protos

and from https://github.com/NebraLtd/hm-pyhelper/tree/master/protos