Add type aliases for higher-dimensional ArcArrays #570

Job	Run time
Pass MSRV values to other jobs	2s
miri	10m 36s
cross_test/i686-unknown-linux-gnu/stable	1m 55s
format/nightly	16s
nostd/thumbv6m-none-eabi/stable	17s
clippy/stable	20s
cargo-careful	2m 6s
cross_test/s390x-unknown-linux-gnu/stable	8m 0s
docs/nightly	20s
blas-msrv	49s
tests/beta	3m 0s
tests/nightly	3m 4s
tests/1.64.0	3m 24s
tests/stable	2m 14s
conclusion	3s
	36m 26s

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