GPU: Add basic texture filtering support

Still has issues around the edges of text.

src/core/gpu_hw.h

@@ -157,6 +157,7 @@ protected:
   u32 m_resolution_scale = 1;
   u32 m_max_resolution_scale = 1;
   bool m_true_color = false;
+  bool m_texture_filtering = false;
   bool m_supports_dual_source_blend = false;
 
   BatchConfig m_batch = {};