Add user functions to AeroProblem's available funcs as normal functionals are

Purpose

The AeroProblem stores a map containing the available functions from the solver. ADflow adds these cost functions in the evalFunctions method, but currently it is implemented only for built-in cost functions, not custom user functions. This PR adds the line needed to include user-specified functionals in the AeroProblem's funcNames map.

Expected time until merged

A few days

Type of change

[x] 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

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 41.08%. Comparing base (cd21478) to head (267b25a). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #365 +/- ## ========================================== + Coverage 41.05% 41.08% +0.02% ========================================== Files 13 13 Lines 4119 4121 +2 ========================================== + Hits 1691 1693 +2 Misses 2428 2428 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

🚨 Try these New Features:

Flaky Tests Detection - Detect and resolve failed and flaky tests

mdolab / adflow