Refactored all grpc methods in method_table (#202)

* refactor grpc methods to be reusable in non-grpc deployment method

* Refactored remaining grpc methods for non-grpc deployment

* Reformatted task methods in method table classes

* Fixed formatting issues

* Removed redundant function definitions

* Assert if task calling create session is text-generation

* Update mii/client.py

* Update mii/grpc_related/modelresponse_server.py

* Update mii/grpc_related/modelresponse_server.py

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Co-authored-by: Michael Wyatt <[email protected]>
Co-authored-by: Tosin Segun <insanechills.com>
Co-authored-by: Michael Wyatt <[email protected]>