Shadow camera settings need to be adjustable

We've noticed that in some cases the default settings Qt 3D Studio picks for the shadow rendering cameras are invalid for the use case artist is trying to implement. E.g. the near plane of the shadow render camera can be too far away for a scene, causing objects close to the light have no shadows.

It seems that for the most part the default settings for the shadow camera are ok, but in some cases artist should be allowed to modify at least near plane, far plane and view angle settings to get a) get shadows visible and to b) optimise the shadow quality for the use case.