diagnostics_channel: add BoundedChannel and scopes #4342

Job	Run time
Build slim tarball	3m 1s
x86_64-linux: with shared libraries	22m 25s
x86_64-darwin: with shared libraries	25m 4s
aarch64-darwin: with shared libraries	20m 28s
aarch64-linux: with shared libraries	18m 34s
	1h 29m 32s

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