Migrate benches to criterion (stable Rust) + clear remaining clippy errors #259

Job	Run time
cross_test/s390x-unknown-linux-gnu/stable	1m 49s
native-backend/stable	8m 47s
format/nightly	30s
clippy/1.94.1	48s
nostd/thumbv6m-none-eabi/stable	28s
Pass MSRV values to other jobs	2s
cross_test/i686-unknown-linux-gnu/stable	1m 42s
cargo-careful	0s
miri	0s
docs/nightly	0s
tests/1.94.0	11m 56s
tests/stable	11m 16s
blas-msrv	1m 19s
tests/beta	11m 56s
conclusion	-1s
	50m 32s

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