Implement --at-least-one-of #2525

Job	Run time
miri	1m 25s
build (aarch64-unknown-linux-gnu)	1m 45s
build (aarch64-unknown-linux-musl)	1m 28s
build (aarch64-apple-darwin)	2m 12s
build (aarch64-pc-windows-msvc)	2m 33s
build (x86_64-unknown-linux-gnu)	1m 9s
build (x86_64-unknown-linux-musl)	1m 16s
build (x86_64-apple-darwin)	1m 52s
build (x86_64-pc-windows-msvc)	2m 28s
build (x86_64-unknown-freebsd)	2m 21s
test (stable)	6m 41s
test (beta)	7m 40s
test (nightly)	6m 21s
test (nightly, macos-11)	10m 50s
test (nightly, windows-2019)	3m 38s
test (1.26)	10m 36s
test (1.30)	10m 37s
test (1.31)	14m 21s
test (1.36)	10m 16s
test (1.39)	12m 34s
test (1.41)	10m 10s
deny / deny	29s
msrv / msrv	1m 5s
tidy / tidy	1m 17s
	2h 5m 4s

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