aes: use `cpubits` crate #964

Job	Run time
build (1.85.0, thumbv7em-none-eabi)	20s
build (1.85.0, wasm32-unknown-unknown)	20s
test (stable)	15s
build (stable, thumbv7em-none-eabi)	12s
build (stable, wasm32-unknown-unknown)	10s
test (1.85.0)	21s
minimal-versions	0s
	1m 38s

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