Adds Distance constarints

[joanibal]

Purpose

Adds a new type of constraint, distance constraints. These constraints have one end that is embedded in the geometry and another end that is fixed. I've found these useful to constrain the distance to a symmetry plane.

I've added functions to add sets of distance constraints or to create them from a polyline.

Expected time until merged

2 weeks

Type of change

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (non-backwards-compatible fix or feature)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no API changes)
• [ ] Documentation update
• [ ] Maintenance update
• [ ] Other (please describe)

Testing

run test_DVConstraint.py

Checklist

• [ ] I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• [ ] I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• [x] I have run unit and regression tests which pass locally with my changes
• [ ] I have added new tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.41379% with 24 lines in your changes missing coverage. Please review.

Project coverage is 65.59%. Comparing base (3404b51) to head (c4852c3).

Files	Patch %	Lines
pygeo/constraints/radiusConstraint.py	0.00%	12 Missing :warning:
pygeo/mphys/mphys_dvgeo.py	0.00%	9 Missing :warning:
pygeo/constraints/DVCon.py	89.28%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #251 +/- ## ========================================== + Coverage 65.47% 65.59% +0.12% ========================================== Files 47 47 Lines 12265 12352 +87 ========================================== + Hits 8030 8102 +72 - Misses 4235 4250 +15 ```

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