Make `udeps` a Rust test #2338

Job	Run time
maybe-expedite	4s
lint	3m 24s
test (third-party, bincode, stable, false)	17m 16s
test (third-party, bincode, stable, true)	18m 14s
test (third-party, bincode, nightly, false)	16m 12s
test (third-party, bincode, nightly, true)	16m 19s
test (third-party, postcard, stable, false)	18m 8s
test (third-party, postcard, stable, true)	17m 51s
test (third-party, postcard, nightly, false)	15m 36s
test (third-party, postcard, nightly, true)	17m 3s
test (other, bincode, stable, false)	31m 8s
test (other, bincode, stable, true)	30m 57s
test (other, bincode, nightly, false)	37m 54s
test (other, bincode, nightly, true)	38m 25s
test (other, postcard, stable, false)	31m 59s
test (other, postcard, stable, true)	31m 59s
test (other, postcard, nightly, false)	36m 59s
test (other, postcard, nightly, true)	39m 24s
all-checks	1s
	6h 58m 53s

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