Performance Updates - Nvidia DLSS and NIS added. Spectator Mode disabled

Added support for Nvidia DLSS on RTX graphics cards. DLSS is set to Ultra Performance by default. User menu settings will follow in a further update.
Added support for Nvidia NIS for non-RTX graphics cards. Again, set to Ultra Performance as default. User settings menu to follow.
Disabled HMD mirroring (Spectator Mode). To re-enable this for video recording etc you can now toggle this on and off by pressing "S" on the keyboard.