Detector suggestion: Angle detector for object - satellite - object angle

Hi,

I think it could be useful with a general angle detector between objects, like object - satellite - object, for example for detecting a low angle between satellite-sun vector and satellite-ground station vector. Use case can be several but including optical reflections from satellites.

A discussion was held at https://forum.orekit.org/t/detector-for-body-sat-ground-station-angle/776

This could be implemented as another constructor of AngleSeparationDetector, or as a separate detector as the definition is a bit different.

Regards /Petrus