Draft: Add PRIME render offload support (Linux)

Hybrid Graphics systems should probably run on the more powerful GPU unless instructed otherwise.

This introduces support for Prime Render Offload to the Linux viewer wrapper script to correct this behavior.

TODO:

• AMD APU + NVIDIA dGPU
• AMD APU + AMD dGPU
• AMD APU + Intel dGPU
• Intel iGPU + NVIDIA gGPU
• Intel iGPU + AMD dGPU
• Intel iGPU + Intel dGPU