Add `MultiProducerSingleConsumerChannel` #12

Job	Run time
Test / Linux (5.8 - jammy)	50s
Test / Windows (5.9 - windows-2022)	15m 16s
Test / Linux (5.9 - jammy)	54s
Test / Linux (5.10 - jammy)	53s
Test / Linux (6.0 - jammy)	1m 6s
Test / Windows (6.0 - windows-2022)	11m 32s
Test / Linux (nightly-main - jammy)	1m 28s
Test / Windows (nightly - windows-2019)	11m 22s
Test / Linux (nightly-6.1 - jammy)	1m 23s
Test / Windows (nightly-6.1 - windows-2019)	9m 58s
Soundness / API breakage check	1m 32s
Soundness / Broken symlinks check	2s
Soundness / Documentation check	1m 13s
Soundness / Format check	40s
Soundness / License headers check	4s
Soundness / Python lint check	4s
Soundness / Shell check	31s
Soundness / YAML lint check	5s
Soundness / Unacceptable language check	4s
	58m 57s

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