3D Shader scopes rendering adjustments

[Redotix]

The purpose of these edits is to allow 3DSS to control the render order of its lenses and provide missing data to fix rendering issues.

Additions:

• custom shader flags for 3DSS lenses with a custom render order
• a render phase for rendering the scope reticle
• a render target that samples the z buffer of the scene before hud rendering begins

[themrdemonized]

thanks