Dubins airplane paths with asymmetric climb rate constraints - #1470

Problem Description
The Dubins airplane assumes that the flight path angle for climbing and descending is identical.

However, for real fixed-wing vehicles this is not the case, as the maximum climb rate depends on the specific excess power, and the minimum climb rate (max descend rate) depends on specific drag of the aircraft. Typically, the smaller absolute value is chosen to keep the Dubins airplane paths feasible.

Solution
This PR sepearates the min and max pitch constraints of the OwenStateSpace such that seperate values can be sued for climbing and descending.

We could show the added feasibility of using higher climb rate constraints resulted in faster solve times for low altitude terrain navigation tasks.

Additional Context
More detail can be found in this paper: https://arxiv.org/abs/2607.15863

@article{lim2026minimum,
  title={Minimum Time Dubins Airplane Paths with Asymmetric Climb Rates},
  author={Lim, Jaeyoung and Loianno, Giuseppe},
  journal={arXiv preprint arXiv:2607.15863},
  year={2026}
}