Add an in-memory transport sample (#664) #609

Job	Run time
build (windows-latest, Debug)	6m 32s
build (macos-latest, Debug)	3m 24s
build (ubuntu-latest, Debug)	3m 56s
build (windows-latest, Release)	5m 45s
build (macos-latest, Release)	4m 14s
build (ubuntu-latest, Release)	4m 13s
publish-coverage / publish-coverage	35s
	28m 39s

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