Add shape function DVs

[anilyil]

Purpose

This PR adds generic shape function DVs to the DVGeo class. This way, the users can specify shape functions that determine what FFD control point will move in what direction. A single shape function can affect multiple FFD points. A single FFD point can be affected by multiple shape functions; the displacements from each shape function are superposed. This also adds shape function DVs to the MPhys wrapper.

No tests yet, but wanted to create the PR to get the ball rolling.

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

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
• [ ] 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

Merging #202 (830c329) into main (45be339) will decrease coverage by 0.03%. The diff coverage is 62.96%.

@@            Coverage Diff             @@
##             main     #202      +/-   ##
==========================================
- Coverage   64.78%   64.76%   -0.03%     
==========================================
  Files          47       47              
  Lines       11969    12018      +49     
==========================================
+ Hits         7754     7783      +29     
- Misses       4215     4235      +20     

Impacted Files	Coverage Δ
pygeo/mphys/mphys_dvgeo.py	0.00% <0.00%> (ø)
pygeo/parameterization/designVars.py	78.64% <72.22%> (-0.62%)	:arrow_down:
pygeo/parameterization/DVGeo.py	68.78% <75.00%> (+<0.01%)	:arrow_up:

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[anilyil]

This one is ready to be reviewed @hajdik, @sseraj. Maybe also @bernardopacini because you guys used this for the aviation paper.

[hajdik]

I added the MPhys wrapper function from my branch.