Add partition(similar to numpy.partition) #438

Job	Run time
format/nightly	15s
clippy/stable	21s
cross_test/i686-unknown-linux-gnu/stable	1m 30s
Pass MSRV values to other jobs	2s
miri	8m 29s
cross_test/s390x-unknown-linux-gnu/stable	7m 39s
cargo-careful	2m 20s
docs/nightly	20s
nostd/thumbv6m-none-eabi/stable	15s
blas-msrv	42s
tests/beta	2m 42s
tests/1.64.0	3m 49s
tests/nightly	3m 21s
tests/stable	3m 1s
conclusion	2s
	34m 48s

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