feat(simd): re-export AMX/VNNI int8 GEMM (matmul_i8_to_i32) through simd.rs #543

Job	Run time
Pass MSRV values to other jobs	2s
nostd/thumbv6m-none-eabi/stable	23s
clippy/1.95.0	39s
native-backend/stable	8m 20s
hpc-stream-parallel/rayon	1m 19s
tier4-avx512-check	27s
format/stable	17s
cross_test/${{ matrix.target }}/${{ matrix.rust }}	-1s
nightly-simd-polyfill	-1s
cargo-careful	-1s
docs/nightly	-6s
miri	-7s
blas-msrv	57s
tests/stable	11m 10s
tests/beta	9m 45s
tests/1.95.0	10m 21s
conclusion	0s
	43m 24s

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