Add tablegen patterns for a variety of FP multiply type instructions.
Adjust generateFMAsInMachineCombiner to return false if SVE is present
in order to combine fmul+fadd into fma. Also add new pseudo instructions
so as to select the most appropriate of FMLA/FMAD depending on register
allocation.
Depends on D96599
This feels like a separate change. I don't see a reason to not fold to FMA when HasFullFP16 in general. (But that would require it's own tests).