[polynomial] Move primitive root attribute to ntt/intt ops. (#93227)

Better design to put semantics on the ops, and in this case the ntt/intt
op can lower in multiple ways depending on the polynomial ring modulus
(it can need an nth root of unity for cyclic polymul -> ntt, or a 2nth
root for negacyclic polymul -> ntt)

---------

Co-authored-by: Jeremy Kun <j2kun@users.noreply.github.com>