Make it easier to do raycasts from Camera

[timothyqiu]

Raycasting from a camera is quite common, but always need boilerplate code like this:

var origin := camera.project_ray_origin(pos)
var normal := camera.project_ray_normal(pos)
var collision := state.intersect_ray(origin, origin + normal * length, ...)

In 4.0, intersect_ray takes a PhysicsRayQueryParameters3D. Maybe add a Camera method to return this parameter?