fix camelcase to be consistent with adflow

[anilyil]

Purpose

Changed instances of coord_xfer to coordXfer based on the changes requested in my ADflow PR: mdolab/adflow#231

Expected time until merged

1-2 days.

Type of change

• Bugfix (non-breaking change which fixes an issue)
• 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

[gawng]

Provided that all the checks pass (they should), this looks good to merge

[codecov]

Codecov Report

Merging #169 (a04aab0) into main (d3f2415) will decrease coverage by 0.83%.
The diff coverage is 84.61%.

@@            Coverage Diff             @@
##             main     #169      +/-   ##
==========================================
- Coverage   64.14%   63.30%   -0.84%     
==========================================
  Files          47       47              
  Lines       11866    11866              
==========================================
- Hits         7611     7512      -99     
- Misses       4255     4354      +99     

Impacted Files	Coverage Δ
pygeo/parameterization/DVGeo.py	66.34% <84.61%> (-0.05%)	⬇️
pygeo/constraints/areaConstraint.py	50.50% <0.00%> (-25.42%)	⬇️
pygeo/constraints/DVCon.py	68.48% <0.00%> (-3.25%)	⬇️

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