Camera model support

[NTK2411]

Is there support for Double Sphere camera model. I couldn't find any such. If it is not present, are there any steps to include it.

[WFram]

DM-VIO doesn't support Double Sphere. But Basalt does.
https://gitlab.com/VladyslavUsenko/basalt-headers/-/blob/master/include/basalt/camera/double_sphere_camera.hpp?ref_type=heads

Adding it to DM-VIO doesn't seem to be complicated.
You can create a new class such as UndistortDS and inherit it from the Undistort class, like it's done for other models. Equations for distortCoordinates can be taken from the code, which I put the reference to above.