Added mesh shifting in multi-section unification component for maintaining LE coincidence

[sabakhshi]

Purpose

Added mesh shifting in multi-section unification component to allow for span/sweep transformations without a constraint. Previously, using a sectional scalar transformation was incompatible with the construction based approach.
With this change the mesh is shifted inboard/outboard to compensate for span, sweep, and dihedral changes of subsequent sections.
The feature is optional but is on by default.
It is fully differentiated with analytic partials.

Expected time until merged

3 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

New tests added/updated. Partials not complex safe so checks with FD enforced.

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