diagnostics_channel: add BoundedChannel and scopes #4814

Job	Run time
Build slim tarball	2m 18s
x86_64-linux: with shared libraries	25m 57s
aarch64-darwin: with shared libraries	19m 15s
x86_64-darwin: with shared libraries	32m 50s
aarch64-linux: with shared libraries	21m 21s
	1h 41m 41s

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