video-texture-target is darkened since THREE 141 update

[netpro2k]

Description
Similar to #5571 video-texture-targets are also darkened.

Screenshots

Additional context
The fix we applied for camera tool isn't quite as easy to apply here since onBeforeRender has to be applied to each object that might have the video-texture-target material on it. Conceptually video-texture-target is a "material component" so it should apply to all objects using that material. In practice we can't actually add aframe components to materials, only objects, so it might be ok to just do the same trick and set onBeforeRender up on the mesh we grab the material from in video-texture-target.

[takahirox]

Three.js has a material.onBeforeRender hook.