Debug overlay commands

[Silverfang22]

Requesting a new set of commands to debug player overlays, such as shields.

Need 4 commands as far as I know, but may request others in the future for other effects, such as bolt-on efx (e.g. on fire), and also bubble shield shaders (e.g. base MP shield effect, instead of the current derivative of SP shield effect -- may open another issue for bubble shields specifically).

JKG_debugOverlay [shaderPath]
JKG_debugOverlayR [0-255]
JKG_debugOverlayG [0-255]
JKG_debugOverlayB [0-255]

The first command will set an overlay over your player (maybe over all player/NPCs?) based on the shader you reference. Do we need a separate command to disable this, or can we set this to 0 once we are done debugging?

The other 3 commands set the RGB value overwrites for the shader, this is for testing various colors on the shaders so we can create a variety of shield effects to be used for the various shield items. We may want to have this semi-standardized though.