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 #49 .

[codecov[bot]]

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 :warning:
ext/QuantumCliffordExt/QuantumCliffordExt.jl	0.00%	2 Missing :warning:
src/QSymbolicsBase/basic_ops_homogeneous.jl	87.50%	1 Missing :warning:

Additional details and impacted files

```diff @@ 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 ```

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