Trac #34147: Implement the quantum Clifford algebra at a root of unity

This works for sufficiently large roots of unity: when q^2k^ != 1. We
provide a new implementation/basis when this q^2k^ = 1.

URL: https://trac.sagemath.org/34147
Reported by: tscrim
Ticket author(s): Travis Scrimshaw
Reviewer(s): Frédéric Chapoton