[Feature Request] Sharp bilinear filtering implementation for output scaling

[MercuryAmalgam]

Quick summary

A less blurry implementation of bilinear output scaling

Details

There are 3 output scaling options present in RPCS3 at the moment:

• Nearest - only really works if your display matches or has 2x the resolution of the output resolution
• Bilinear - blurrier than the 720p output of a real PS3 displayed on a TV
• FSR1 - rounds off sharp corners on all sharpness settings

For users who can't or prefer not to use increased resolution scaling (due to performance, visual glitches etc.) - there is no output mode setting that could present a nicely scaled picture without excessive blurring (bilinear), shimmer (nearest) or scaling artifacts (FSR1) on 1080p displays in most games

Other emulators such as Duckstation, PCSX2, Dolphin and others - have a "sharp bilinear" output filtering implementation
It works by maintaining the sharpness of an integer scaling while performing some blending to reduce shimmering artifacts

• What part of RPCS3 would be affected by your feature? (Gameplay, Debugging, UI, Patches, Installation, CI etc.)
  Game visuals, output scaling method implementation + UI option

• Why your feature is important to RPCS3.
  It would allow users with displays that don't match the output resolution (usually 720p) or can't use resolution scaling to enjoy a sharp image without apparent scaling artifacts

• If the feature is implemented in other projects, attach screenshots.
  The feature can be found at the very least in the Duckstation, PCSX2 and Dolphin emulators:
  
  
  

Here is an example implementation for another project, with source code:
https://github.com/rsn8887/Sharp-Bilinear-Shaders

Please consider implementing this feature

[MercuryAmalgam]

Got a new PS3 - so made a comparison between integer, bilinear on RPCS3 at 720p and an actual PS3
As you can see at native res RPCS3 on bilinear is more blurry, on integer it's way pixelated - no mode matches the PS3's output
Increasing internal res improves things, but requires more resources and can have glitches