Extend MixedIntegerLinearProgram.get_values so it can convert inexact integer values from numerical solvers to ZZ and bool, with tolerance checking.

We apply it to one use of MIP in sage.graphs.

Other fixes using the new option will be tracked in #32191.

CC: @mkoeppe @tscrim @dimpase @DaveWitteMorris @seblabbe

Component: graph theory

Author: David Coudert, Matthias Koeppe

Branch/Commit: db83853

Reviewer: David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/32197