Move fileutil, net, image loaders, ui to Common. (#13506)

* Move and rename file_util/fd_util to Common/File/FileUtil and DirListing

Let's also move net while we're at it.

Move the ZIM/PNG loaders over to Common.

Move the UI framework into Common

iOS buildfix

* Buildfix

* Buildfixes

* Apple buildfix

* This typo again..

* UWP buildfix

* Fix build of PPSSPPQt, such as it is (it's not in good condition...)

* Guess what? Another buildfix.

Core/Config.cpp

@@ -25,8 +25,8 @@
 #include "ppsspp_config.h"
 
 #include "gfx_es2/gpu_features.h"
-#include "net/http_client.h"
-#include "net/url.h"
+#include "Common/Net/HTTPClient.h"
+#include "Common/Net/URL.h"
 
 #include "Common/Log.h"
 #include "Common/Data/Format/IniFile.h"
@@ -34,7 +34,7 @@
 #include "Common/Data/Text/I18n.h"
 #include "Common/Data/Text/Parsers.h"
 #include "Common/CPUDetect.h"
-#include "Common/FileUtil.h"
+#include "Common/File/FileUtil.h"
 #include "Common/LogManager.h"
 #include "Common/OSVersion.h"
 #include "Common/System/Display.h"