Add `MultiProducerSingleConsumerChannel` #7

Job	Run time
Test / Linux (5.8 - jammy)	44s
Test / Windows (5.9 - windows-2022)	10m 27s
Test / Linux (5.9 - jammy)	51s
Test / Windows (6.0 - windows-2022)	12m 25s
Test / Linux (5.10 - jammy)	50s
Test / Windows (nightly - windows-2019)	10m 20s
Test / Linux (6.0 - jammy)	53s
Test / Windows (nightly-6.1 - windows-2019)	10m 33s
Test / Linux (nightly-main - jammy)	1m 24s
Test / Linux (nightly-6.1 - jammy)	1m 23s
Soundness / API breakage check	53s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	1m 8s
Soundness / Format check	35s
Soundness / License headers check	6s
Soundness / Shell check	32s
Soundness / Unacceptable language check	3s
Soundness / YAML lint check	3s
Soundness / Python lint check	6s
	53m 20s

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