Adds an array reference type #408

Job	Run time
clippy/stable	11s
Pass MSRV values to other jobs	2s
format/nightly	14s
cross_test/i686-unknown-linux-gnu/stable	1m 1s
miri	7m 9s
cross_test/s390x-unknown-linux-gnu/stable	1m 3s
nostd/thumbv6m-none-eabi/stable	11s
cargo-careful	57s
docs/nightly	20s
blas-msrv	35s
tests/beta	24s
tests/stable	30s
tests/1.64.0	26s
tests/nightly	23s
conclusion	2s
	13m 28s

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