This commons out a chunk of the different two operand MVE patterns into a single helper multidef. Or technically two multidef patterns so that the Dup qr patterns can also get the same treatment. This is most of the two address instructions that we have some codegen pattern for (not ones that we select purely from intrinsics). It does not include shifts, which are more spread out and will need some extra work to be given the same treatment.
This is causing runtime failures in at least ffmpeg, libvpx and dav1d, when targeting armv7-w64-mingw32, so it doesn't seem to be NFC as intended. I'll try to get a small reproducer later today...