Implement XCVsimd intrinsics for CV32E40P according to the specification.
This commit is part of a patch-set to upstream the 7 vendor specific extensions of CV32E40P.
Contributors: @CharKeaney, @jeremybennett, @lewis-revill, @liaolucy, Nandni Jamnadas, @PaoloS, @simoncook, @xmj.
I think per the discussion in another thread, this should actually be 1.0.