express, qsimplify, and latexify updates

[apkille]

• Added a doc that describes features of express and added more tests in test_express_cliff.jl.
• qsimplify can now traverse through subexpressions using Prewalk from SymbolicUtils.jl. This required defining maketerm from TermInterface.jl for each symbolic operation.
• Added latexify capabilities and fixed bug mentioned in latexify partially broken after #40 #49 .

[Krastanov]

Looks good! Feel free to merge after addressing the comments if tests pass.

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 20 lines in your changes missing coverage. Please review.

Project coverage is 66.25%. Comparing base (4df75a0) to head (6f7f5f4).
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/QSymbolicsBase/latexify.jl	0.00%	17 Missing ⚠️
ext/QuantumCliffordExt/QuantumCliffordExt.jl	0.00%	2 Missing ⚠️
src/QSymbolicsBase/basic_ops_homogeneous.jl	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #57      +/-   ##
==========================================
+ Coverage   65.76%   66.25%   +0.48%     
==========================================
  Files          15       15              
  Lines         628      646      +18     
==========================================
+ Hits          413      428      +15     
- Misses        215      218       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

Permission to merge after tests pass and comments are addressed.