Replace `all_is_cubes::util::CustomFormat` with `manyfmt` library. #168

Job	Run time
miri	2m 31s
no_std	50s
build (ubuntu, stable, locked, true)	56m 14s
build (windows, stable, locked, false)	31m 1s
build (macos, stable, locked, false)	1h 20m 2s
build (ubuntu, nightly, locked, false)	17m 26s
build (ubuntu, beta, locked, false)	16m 49s
build (ubuntu, stable, latest, false)	18m 43s
build (ubuntu, stable, minimal, false)	29m 31s
fuzz	18m 18s
deploy	9s
	4h 31m 34s

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