GS: Support saving WebP screenshots

pcsx2-qt/Settings/GraphicsSettingsWidget.ui

@@ -426,6 +426,11 @@
              <string>JPEG</string>
             </property>
            </item>
+           <item>
+            <property name="text">
+             <string>WebP</string>
+            </property>
+           </item>
           </widget>
          </item>
          <item>

pcsx2/Config.h

@@ -326,6 +326,7 @@ enum class GSScreenshotFormat : u8
 {
 	PNG,
 	JPEG,
+	WebP,
 	Count,
 };
 

pcsx2/GS/Renderers/Common/GSRenderer.cpp

@@ -422,7 +422,7 @@ static GSVector4i CalculateDrawSrcRect(const GSTexture* src, const GSVector2i re
 static const char* GetScreenshotSuffix()
 {
 	static constexpr const char* suffixes[static_cast<u8>(GSScreenshotFormat::Count)] = {
-		"png", "jpg"};
+		"png", "jpg", "webp"};
 	return suffixes[static_cast<u8>(GSConfig.ScreenshotFormat)];
 }
 

pcsx2/ImGui/FullscreenUI.cpp

@@ -3219,6 +3219,7 @@ void FullscreenUI::DrawGraphicsSettingsPage()
 	static constexpr const char* s_screenshot_formats[] = {
 		FSUI_NSTR("PNG"),
 		FSUI_NSTR("JPEG"),
+		FSUI_NSTR("WebP"),
 	};
 
 	SettingsInterface* bsi = GetEditingSettingsInterface();