Split supported message into RequestMessage and ResponseMessage #66

Job	Run time
build-linux (stable)	2m 41s
build-linux (beta)	2m 34s
clippy / clippy	1m 13s
code-coverage / cov	4m 13s
verify-clean-codegen / types	46s
verify-clean-supported-message / supported_message	13s
verify-clean-node-ids / node_ids	5s
verify-code-formatting / fmt	8s
	11m 53s

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