[buffer_cache] Add option to control GPU buffer readback (#4126)

Added an option to control the GPU buffer readback, as it causes issues if the hardware cannot keep up with the additional workload.

Some games require this to render certain effects properly.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4126

src/common/settings.h

@@ -573,6 +573,13 @@ struct Values {
         false,
 #endif
         "rescale_hack", Category::RendererHacks};
+    SwitchableSetting<bool> enable_gpu_buffer_readback{linkage,
+                                                       false,
+                                                       "enable_gpu_buffer_readback",
+                                                       Category::RendererAdvanced,
+                                                       Specialization::Default,
+                                                       true,
+                                                       true};
 
     SwitchableSetting<bool> use_asynchronous_shaders{linkage, false, "use_asynchronous_shaders",
                                                      Category::RendererHacks};