Logging: Add customizable logging backends and fmtlib based macros

* Change the logging backend to support multiple sinks through the
Backend Interface
* Add a new set of logging macros to use fmtlib instead.
* Qt: Compile as GUI application on windows to make the console hidden by
default. Add filter configuration and a button to open log location.
* SDL: Migrate to the new logging macros

src/core/settings.cpp

@@ -4,14 +4,13 @@
 
 #include "audio_core/dsp_interface.h"
 #include "core/core.h"
+#include "core/frontend/emu_window.h"
 #include "core/gdbstub/gdbstub.h"
 #include "core/hle/service/hid/hid.h"
 #include "core/hle/service/ir/ir.h"
 #include "core/settings.h"
 #include "video_core/video_core.h"
 
-#include "core/frontend/emu_window.h"
-
 namespace Settings {
 
 Values values = {};