[GlobalOpt] Keep strided input maps when the producer can fuse (#24950)

Factoring `dim * cst` strides out of a contraction-like generic inserts
a strided `tensor.extract_slice` between the contraction and its input.
When the input has an elementwise producer (a dequantize feeding a 1x1
stride-2 convolution, say), the slice blocks both fusion paths:
elementwise fusion requires the producer to directly define the
consumer's operand, and tile-based producer fusion only supports
unit-stride slices. Codegen falls back to materializing the producer as
a whole-tensor stack allocation in every workgroup: a 3.2 MB alloca for
a 1x256x56x56xf32 dequantize, well over the 32 KB stack limit, and the
compile fails.

Skip the factoring only when the strided input's producer can fuse
elementwise into the contraction and into every other user of its
result, so the fusion actually eliminates the producer. Codegen then
merges the producer into the contraction, which reads the input directly
through the strided map with no intermediate tensor. Producers that are
materialized anyway (e.g. a result also returned from the function) keep
the factored projected-permutation input map.

Strided contractions with a fusable producer now lower through the
generic path instead of contraction selection such as AMDGPU MFMA, the
original motivation for the factoring, in exchange for eliminating the
intermediate tensor. Strided contractions on dispatch-boundary inputs
keep the factored form.

Fixes #24752

Tests: iree-opt --split-input-file --mlir-print-local-scope
-iree-global-opt-convert-strided-contraction-to-contraction
compiler/src/iree/compiler/GlobalOptimization/test/strided_contraction_to_contraction.mlir

Signed-off-by: zhangpan <98025960+zhangpan2001@users.noreply.github.com>
Co-authored-by: OpenAI <noreply@openai.com>