`sage.numerical.interactive_simplex_method`: improve support for base fields other than `QQ` and `RDF`

[mkoeppe]

We remove the ad-hoc conversion of data to RDF in InteractiveLPProblem.feasible_set. This is outdated and problematic:

• the polyhedra code over RDF is not robust at all
• Sage has good support for algebraic polyhedra, in particular via normaliz.

We also make the printing code in _latex_product more robust:

• it no longer relies on SR to decide whether a coefficient needs to be wrapped in parens; instead, we use the same simple test that sage.misc.repr.coeff_repr already uses
• recognizing trivial coefficients (0, 1) is switched to comparing text instead of comparing elements - in order to support fields such as SR where == is magic

Rebased version of:

• 31312

Author: @mkoeppe, @ComboProblem

Resolves #31312.

:memo: Checklist

• [x] The title is concise and informative.
• [x] The description explains in detail what this PR is about.
• [x] I have linked a relevant issue or discussion.
• [ ] I have created tests covering the changes.
• [ ] I have updated the documentation and checked the documentation preview.

:hourglass: Dependencies

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[mkoeppe]

@ComboProblem I've copied in the ticket description from the old ticket https://github.com/sagemath/sage/issues/31312. Part of what it's promising:

• recognizing trivial coefficients (0, 1) is switched to comparing text instead of comparing elements - in order to support fields such as SR where == is magic

Could you add a test that uses an LP with coefficients from SR (for example, constant symbolic expressions such as pi or log(2) or sqrt(5))