Make arbitrary mipmap detection toggle invalidate the texture cache

We want this setting to invalidate the cache because it may affect the appearance of textures in the rendered scene, therefore one would expect changing it while the game is running to have the expected effect immediately.

Source/Core/VideoCommon/TextureCacheBase.h

@@ -357,6 +357,7 @@ private:
     bool efb_mono_depth;
     bool gpu_texture_decoding;
     bool disable_vram_copies;
+    bool arbitrary_mipmap_detection;
   };
   BackupConfig backup_config = {};
 };