Make `udeps` a Rust test #2336

Job	Run time
maybe-expedite	2s
lint	3m 27s
test (third-party, bincode, stable, false)	18m 7s
test (third-party, bincode, stable, true)	17m 26s
test (third-party, bincode, nightly, false)	16m 6s
test (third-party, bincode, nightly, true)	15m 53s
test (third-party, postcard, stable, false)	20m 9s
test (third-party, postcard, stable, true)	17m 57s
test (third-party, postcard, nightly, false)	16m 23s
test (third-party, postcard, nightly, true)	16m 15s
test (other, bincode, stable, false)	30m 26s
test (other, bincode, stable, true)	30m 55s
test (other, bincode, nightly, false)	35m 48s
test (other, bincode, nightly, true)	37m 20s
test (other, postcard, stable, false)	32m 45s
test (other, postcard, stable, true)	31m 20s
test (other, postcard, nightly, false)	37m 46s
test (other, postcard, nightly, true)	37m 39s
all-checks	1s
	6h 55m 45s

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