feat(burn): AttentionTable intercept in matmul — O(1) table lookup path #40

Job	Run time
cross_test/s390x-unknown-linux-gnu/stable	1m 36s
nostd/thumbv6m-none-eabi/stable	24s
clippy/stable	25s
native-backend/stable	37s
format/stable	22s
cross_test/i686-unknown-linux-gnu/stable	1m 35s
Pass MSRV values to other jobs	2s
cargo-careful	0s
docs/nightly	0s
miri	0s
blas-msrv	51s
tests/1.64.0	1m 20s
tests/beta	1m 21s
tests/stable	1m 23s
conclusion	0s
	9m 56s

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