Export `mpsc` channel receviers #550

Job	Run time
signet	1m 7s
bitcoind	2m 22s
build (ubuntu-latest, 1.63.0)	2m 40s
build (ubuntu-latest, stable)	2m 37s
build (ubuntu-latest, beta)	2m 52s
build (ubuntu-latest, nightly)	2m 44s
build (macos-latest, 1.63.0)	2m 27s
build (macos-latest, stable)	2m 14s
build (macos-latest, beta)	2m 46s
build (macos-latest, nightly)	2m 11s
build (windows-latest, 1.63.0)	3m 14s
build (windows-latest, stable)	3m 21s
build (windows-latest, beta)	3m 10s
build (windows-latest, nightly)	3m 15s
	37m 0s

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