This module provides a "clean" dictionary view on a dictionary with
floating-point numbers. Cleaning means to change almost-zeros to exact
zeros, allowing the Interactive Simplex Method to recognize primal and
dual feasibility and to avoid pivoting on zero pivot elements.

(Split out from the larger ticket #18804.)

Depends on #20874

CC: @uduse @pgxiao

Component: numerical

Author: Aedi Wang

Branch/Commit: u/mkoeppe/lpcleandictionary___floating_point_helper_class_for_interactive_simplex_method @ ae348f7

Reviewer: Michael Orlitzky

Issue created by migration from https://trac.sagemath.org/ticket/20203