Restructure `IMcpEndpoint`, `IMcpClient`, and `IMcpServer` #726

Job	Run time
build (ubuntu-latest, Debug)	1m 44s
build (macos-latest, Release)	1m 5s
build (ubuntu-latest, Release)	2m 14s
build (macos-latest, Debug)	1m 52s
build (windows-latest, Debug)	2m 27s
build (windows-latest, Release)	2m 44s
publish-coverage	0s
	12m 6s

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