Expose the GLPK functions get_col_stat, get_row_stat in Sage's GLPKBackend class.

These functions are essential for any serious linear programming.
For example, if one wants to extract the exact rational basic solution from the dictionary, one needs the information returned by these functions.

CC: @nathanncohen @yuan-zhou

Component: numerical

Keywords: glpk

Author: Yuan Zhou

Branch/Commit: 30eef17

Reviewer: Nathann Cohen

Issue created by migration from https://trac.sagemath.org/ticket/18685