texture_cache: Blacklist BGRA8 copies and views on OpenGL

In order to force the BGRA8 conversion on Nvidia using OpenGL, we need to forbid texture copies and views with other formats.

This commit also adds a boolean relating to this, as this needs to be done only for the OpenGL api, Vulkan must remain unchanged.

src/video_core/renderer_vulkan/vk_texture_cache.h

@@ -93,6 +93,11 @@ struct TextureCacheRuntime {
         // No known Vulkan driver has broken image views
         return false;
     }
+
+    bool HasNativeBgr() const noexcept {
+        // All known Vulkan drivers can natively handle BGR textures
+        return true;
+    }
 };
 
 class Image : public VideoCommon::ImageBase {