algebra: poly: poly, authenticated-poly: Implement polynomial division methods

[joeykraut]

Purpose

This PR implements polynomial division on both public and shared polynomials. In both cases, this is floor division. For shared polynomials, both parties can locally compute the division operation when the divisor is public -- this generates secret shares of the quotient polynomial as explained in the code.

Testing

• All unit and integration tests pass
• Tested all new arithmetic operations

[akirillo]

mostly questions that i trust you to have considered, but there are a couple small changes (i think) that are necessary

[akirillo]

thanks for answering the qs, lgtm now!