implement dot for higher-dimensional arrays with Ix2 #668

Job	Run time
miri	11m 36s
format/nightly	15s
nostd/thumbv6m-none-eabi/stable	19s
cross_test/s390x-unknown-linux-gnu/stable	8m 26s
cross_test/i686-unknown-linux-gnu/stable	2m 55s
Pass MSRV values to other jobs	2s
docs/nightly	21s
clippy/stable	28s
cargo-careful	2m 8s
tests/beta	2m 52s
blas-msrv	35s
tests/nightly	3m 35s
tests/stable	3m 11s
tests/1.87.0	2m 41s
conclusion	-1s
	39m 23s

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