Add "Output Resampling" option (#1541)

Adds an Output Resampling option to the Video tab to allow choosing between the old Bilinear sampler and a new Area sampler. Area sampling produces a much cleaner, softer image when downscaling, and a significantly sharper image when upscaling. This can also serve as a halfway decent anti-aliasing substitute until we have a more proper implementation.

src/dusk/settings.cpp

@@ -63,6 +63,7 @@ UserSettings g_userSettings = {
         .enableFrameInterpolation {"game.enableFrameInterpolation", FrameInterpMode::Off},
         .internalResolutionScale {"game.internalResolutionScale", 0},
         .shadowResolutionMultiplier {"game.shadowResolutionMultiplier", 1},
+        .resampler {"game.resampler", Resampler::Bilinear},
         .enableDepthOfField {"game.enableDepthOfField", true},
         .enableMapBackground {"game.enableMapBackground", true},
         .disableCutscenePillarboxing {"game.disableCutscenePillarboxing", false},
@@ -223,6 +224,7 @@ void registerSettings() {
     Register(g_userSettings.game.disableWaterRefraction);
     Register(g_userSettings.game.enableTextureReplacements);
     Register(g_userSettings.game.internalResolutionScale);
+    Register(g_userSettings.game.resampler);
     Register(g_userSettings.game.shadowResolutionMultiplier);
     Register(g_userSettings.game.enableDepthOfField);
     Register(g_userSettings.game.enableMapBackground);