Make `udeps` a Rust test #2337

Job	Run time
maybe-expedite	4s
lint	3m 34s
test (third-party, bincode, stable, false)	17m 16s
test (third-party, bincode, stable, true)	17m 34s
test (third-party, bincode, nightly, false)	16m 47s
test (third-party, bincode, nightly, true)	15m 52s
test (third-party, postcard, stable, false)	18m 5s
test (third-party, postcard, stable, true)	17m 28s
test (third-party, postcard, nightly, false)	16m 5s
test (third-party, postcard, nightly, true)	16m 5s
test (other, bincode, stable, false)	31m 40s
test (other, bincode, stable, true)	30m 38s
test (other, bincode, nightly, false)	36m 16s
test (other, bincode, nightly, true)	36m 34s
test (other, postcard, stable, false)	30m 48s
test (other, postcard, stable, true)	33m 36s
test (other, postcard, nightly, false)	37m 3s
test (other, postcard, nightly, true)	37m 29s
all-checks	1s
	6h 52m 55s

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