refactor and removal of redundant neutronics/h5m related code

[shimwell]

Proposed changes

Adds export_brep() to Shape and Reactor class and removes redundant attributes (stp_filename, stl_filename, material_tags)

The paramak use to contain the ability to export h5m files and perform neutronics simulations as it was restritect to a single repository. The ability to export h5m files is now rewritten and in the cad_to_h5m package and the ability to run neutronics simulations is now in the openmc-dagmc-wrapper package. This allows for a decent amount of code removal as the paramak can now focus on creating geometry solely.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Pep8 applied
• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[codecov]

Codecov Report

Attention: Patch coverage is 86.15385% with 9 lines in your changes missing coverage. Please review.

Project coverage is 96.84%. Comparing base (ac19508) to head (02c89e7).
Report is 803 commits behind head on main.

Files	Patch %	Lines
paramak/reactor.py	78.57%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
- Coverage   98.22%   96.84%   -1.38%     
==========================================
  Files          76       76              
  Lines        4895     4724     -171     
==========================================
- Hits         4808     4575     -233     
- Misses         87      149      +62     

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