Add comparison operations

[lemaitre]

Is there any plan to have mask types? Because those comparison instructions would definitely generate masks if they exist. Typically, AVX512 and SVE comparisons do generate masks and not vectors.

[penzn]

Good point - we would need to balance operations returning masks and operations setting lanes. I am going to add a note documenting this. Masking ops are not forgotten - we would definitely need to evaluate them.