gltf: matching lighting between blender and godot

[yankscally]

each light will need its own special implementation.

• match the visual lighting between the apps somehow...

• the light factor in gltf is multiplied by around 680 - need to find the exact number

• fix sunlight/directional.
  doesnt use Watts and has default strength value of 10.
  using the 680 factor we can get that the same in godot, however, the actual light levels what you see are much different
  
  10 is also the max value for a "sun" light in blender.

• omni light has a range of 4096 on import. not sure how to fix this yet.

• spotlight seems to work fine, but will check it over anyway