Implement fast evaluation of MacLane key polynomials

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Key polynomials can be evaluated more quickly with Proposition 3.8 of https://arxiv.org/pdf/1005.1156.pdf.

Migrated from https://github.com/saraedum/mac_lane/issues/1.

CC:  @sagetrac-swewers

Component: **commutative algebra**

Keywords: **maclane, valuations**

_Issue created by migration from https://trac.sagemath.org/ticket/24913_

