[LV] Add ExtNegatedMulAccReduction expression type
This PR adds the ExtNegatedMulAccReduction expression type for
VPExpressionRecipe so that extend-multiply-accumulate reductions with a
negated multiply can be bundled.
Stacked PRs:
1. https://github.com/llvm/llvm-project/pull/156976
2. -> This
3. https://github.com/llvm/llvm-project/pull/147302