Make Expression.simplify optionally use sympy

[mathcals]

📚 Description

Expression.simplify currently uses maxima to simplify an expression. Sympy also has a method simplify that often works better. For this reason I propose to add an 'algorithm' parameter to the Expression.simplify method, to make it easy to use sympy's simplification method.

To illustrate why this is beneficial, consider the expression x = (-1/5*(2*sqrt(6)*(sqrt(5) - 5) + 11*sqrt(5) - 11)/(2*sqrt(6)*sqrt(5) - 11)). Both x.simplify_full() and x.simplify() are not able to simplify this expression. However, x.simplify(algorithm='sympy') would return 1/5*sqrt(5) - 1/5.

📝 Checklist

• I have made sure that the title is self-explanatory and the description concisely explains the PR.
• I have linked an issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[codecov-commenter]

Codecov Report

Patch coverage: 97.95% and project coverage change: +0.02 🎉

Comparison is base (52a81cb) 88.57% compared to head (cd39e30) 88.60%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #35236      +/-   ##
===========================================
+ Coverage    88.57%   88.60%   +0.02%     
===========================================
  Files         2140     2140              
  Lines       397273   397415     +142     
===========================================
+ Hits        351891   352117     +226     
+ Misses       45382    45298      -84     

Impacted Files	Coverage Δ
src/sage/schemes/elliptic_curves/ell_generic.py	93.11% <66.66%> (-0.12%)	⬇️
src/sage/interfaces/tachyon.py	87.93% <90.00%> (+0.43%)	⬆️
src/sage/schemes/elliptic_curves/gal_reps.py	82.23% <90.00%> (+0.04%)	⬆️
src/sage/quadratic_forms/quadratic_form.py	90.26% <95.65%> (+0.16%)	⬆️
src/sage/modular/quasimodform/element.py	99.20% <100.00%> (+0.06%)	⬆️
src/sage/rings/qqbar.py	95.30% <100.00%> (+<0.01%)	⬆️
src/sage/schemes/affine/affine_morphism.py	90.33% <100.00%> (ø)
src/sage/schemes/elliptic_curves/BSD.py	43.75% <100.00%> (+0.21%)	⬆️
src/sage/schemes/elliptic_curves/cardinality.py	87.54% <100.00%> (+0.93%)	⬆️
src/sage/schemes/elliptic_curves/cm.py	89.52% <100.00%> (+0.39%)	⬆️
... and 70 more

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[mkoeppe]

Documentation does not build

[mathcals]

The documentation should build now.

[github-actions]

Documentation preview for this PR is ready! 🎉
Built with commit: cd39e30

[mkoeppe]

Yes, that worked – https://deploy-preview-35236--sagemath-tobias.netlify.app/reference/calculus/sage/symbolic/expression.html#sage.symbolic.expression.Expression.simplify

[mkoeppe]

The test failures are unrelated sporadic errors.

[mkoeppe]

LGTM. Thanks for this contribution!