[mlir][vector] Add patterns to simplify chained reductions (#73048)

Chained reductions get created during vector unrolling. These patterns
simplify them into a series of adds followed by a final reductions.

This is preferred on GPU targets like SPIR-V/Vulkan where vector
reduction gets lowered into subgroup operations that are generally more
expensive than simple vector additions.

For now, only the `add` combining kind is handled.