Update trajectory figures

[teubert]

Update the way trajectory figures are generated to be a little more general.

The function in UAVModel still works the same as before, but now theres a function to explore a reference trajectory and it can be used outside of the UAVModel. This is important for when it's used with prog_server

[github-actions[bot]]

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[codecov-commenter]

Codecov Report

Attention: 34 lines in your changes are missing coverage. Please review.

Comparison is base (bda3c9e) 83.41% compared to head (0ff35ab) 83.27%.

Files	Patch %	Lines
src/progpy/utils/traj_gen/trajectory.py	24.13%	22 Missing :warning:
...c/progpy/models/aircraft_model/small_rotorcraft.py	14.28%	12 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #136 +/- ## ========================================== - Coverage 83.41% 83.27% -0.14% ========================================== Files 100 100 Lines 10461 10488 +27 ========================================== + Hits 8726 8734 +8 - Misses 1735 1754 +19 ```

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