Fix bug for wave ports

[sebastiangrimberg]

• Fix wave ports bug where the quadrature order was not being set correctly, and thus the eigenvalue solve would fail (especially for high-order).
• Revisited wave port formulation, making a small update to use the variational formulation from https://www.jstor.org/stable/4099985 (see also https://arxiv.org/abs/2302.11994, both replace https://ieeexplore.ieee.org/iel1/22/2793/00085399.pdf) which improves the eigenvalue problem by avoiding the introduction of many modes at \beta = 0.

Note: The re-baselined regression tests for cpw/cpw_wave_uniform and cpw/cpw_wave_adaptive are expected: The quadrature rule fix changes the computed mode shape slightly which affects both the propagation constant as well as the excitation of the model in the driven solve. The changes (all seem to be on the order of a few percent) seem justified in this regard.