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.

UI/NativeApp.cpp

@@ -43,16 +43,16 @@
 #include "Windows/CaptureDevice.h"
 #endif
 
-#include "net/http_client.h"
-#include "net/resolve.h"
+#include "Common/Net/HTTPClient.h"
+#include "Common/Net/Resolve.h"
 #include "gfx/texture_atlas.h"
 #include "gfx_es2/draw_text.h"
 #include "gfx_es2/gpu_features.h"
 #include "thin3d/thin3d.h"
-#include "ui/ui.h"
-#include "ui/screen.h"
-#include "ui/ui_context.h"
-#include "ui/view.h"
+#include "Common/UI/UI.h"
+#include "Common/UI/Screen.h"
+#include "Common/UI/Context.h"
+#include "Common/UI/View.h"
 #include "android/jni/app-android.h"
 
 #include "Common/System/Display.h"
@@ -68,7 +68,7 @@
 #include "Common/File/VFS/VFS.h"
 #include "Common/File/VFS/AssetReader.h"
 #include "Common/CPUDetect.h"
-#include "Common/FileUtil.h"
+#include "Common/File/FileUtil.h"
 #include "Common/TimeUtil.h"
 #include "Common/StringUtils.h"
 #include "Common/LogManager.h"