added export_html_3d method

[shimwell]

Proposed changes

This PR adds the export_html_3d to the Shape and Reactor class.

The new method allows stand alone 3d interactive objects to be viewed in html files

Types of changes

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] 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)
• [x] 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[bot]]

Codecov Report

Merging #841 (5e95072) into develop (4532617) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #841   +/-   ##
========================================
  Coverage    94.67%   94.68%           
========================================
  Files           75       75           
  Lines         5393     5401    +8     
========================================
+ Hits          5106     5114    +8     
  Misses         287      287           

Impacted Files	Coverage Δ
paramak/reactor.py	91.87% <100.00%> (+0.07%)	:arrow_up:
paramak/shape.py	97.87% <100.00%> (+0.01%)	:arrow_up:

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