UT469d: Speed improvements, full fullscreen support, better font drawing

This is another large update. Speed has been increased again, and it's neck and neck with all the other renderers for the top slot. For AMD users, this driver will outperform almost all of the other ones, while for NVidia users its only a few frames behind. FPS minimums have been brought up too, so there should be very little frame-to-frame gaps. Image quality has also seen a big boost, especially when running with MSAA on.

Notable changes:

• Supports the DX12 feature "Forced Sample count of 1" in order to draw font characters with maximum clarity, even when rendering with MSAA on
• Full support for fullscreen, with all known issues fixed, detection for invalid resolutions implemented, etc.
• Further HDR improvements (I just got a HDR monitor myself too)
• Fixed a memory leak when closing down the driver (only noticeable in the editor)
• Made macro and detail textures apply at 2x strength, to match lightmap strength
• Fixed UV clamping issues when using HD textures
• Support "invalid" HD textures by decompressing them first
• Fixed tile rendering being off by one pixel on NVidia GPUs
• Added in caching for the Windows detected HDR white balance level. If this value is different between the current run and the last run, it resets the HDRWhiteBalance config value back to the Windows queried default. This fixes an issue where the value doesn't get updated when the user changes monitors or Windows HDR settings.