[Matrix] Add special case dot product lowering

[Matrix] Add special case dot product lowering

Add special case to matrix lowering for dot products. Normal matrix lowering if optimized for either row-major or column-major, which results in many `shufflevector` instructions being generated for one vector. We work around this in our special case. We can also use vector-reduce adds instead of sequential adds to sum the result of the element-wise multiplication, which takes advantage of SIMD instructions.

Reviewed By: fhahn, thegameg

Differential Revision: https://reviews.llvm.org/D131125