iPhone X support and iOS-related fixes

Starting from April 2018 Apple no longer accepts apps that do not
support iPhone X. For games this mainly means respecting the safe area,
unobstructed by notch and virtual home button. UI controls must be
placed within the safe area so that users can interact with them.

This commit:

- Adds OS::get_window_safe_area method that returns unobscured area of
  the window, where interactive controls should be rendered.

- Reorganizes how launch screens are exported - the previous way was
  incorrect and modern iPhones did not pick up the correct screens and
  because of that used a non-native resolution to render the game.

- Adds launch screen options for iPhone X.

- Makes launch screens optional in the export template. If not
  specified, a white screen will be used.

- Adds App Store icon (1024x1024) export option as it now has to be
  bundled with the app instead of being provided in iTunes Connect.

- Fixes crash when launching games in iOS Simulator. It happened because
  controllerWasConnected callback came before the engine was
  initialized. Now in such case the controllers will be queued up and
  registered after initialization is done.

- Fixes issue with the virtual keyboard where for some reason
  autocorrection panel would intersect with the keyboard itself and not
  allow you to use the top row of the keyboard. This is fixed by
  disabling autocorrection altogether.

Closes godotengine#17358. Fixes godotengine#17428. Fixes godotengine#17331.

(cherry picked from commit 1d9a3a9)

core/bind/core_bind.h

@@ -164,6 +164,7 @@ class _OS : public Object {
 	virtual void set_window_position(const Point2 &p_position);
 	virtual Size2 get_window_size() const;
 	virtual Size2 get_real_window_size() const;
+	virtual Rect2 get_window_safe_area() const;
 	virtual void set_window_size(const Size2 &p_size);
 	virtual void set_window_fullscreen(bool p_enabled);
 	virtual bool is_window_fullscreen() const;

core/os/os.h

@@ -215,6 +215,18 @@ class OS {
 	virtual void request_attention() {}
 	virtual void center_window();
 
+	// Returns window area free of hardware controls and other obstacles.
+	// The application should use this to determine where to place UI elements.
+	//
+	// Keep in mind the area returned is in window coordinates rather than
+	// viewport coordinates - you should perform the conversion on your own.
+	//
+	// The maximum size of the area is Rect2(0, 0, window_size.width, window_size.height).
+	virtual Rect2 get_window_safe_area() const {
+		Size2 window_size = get_window_size();
+		return Rect2(0, 0, window_size.width, window_size.height);
+	}
+
 	virtual void set_borderless_window(bool p_borderless) {}
 	virtual bool get_borderless_window() { return 0; }
 

platform/iphone/app_delegate.mm

@@ -140,42 +140,6 @@ void _ios_add_joystick(GCController *controller, AppDelegate *delegate) {
 	};
 }
 
-static void on_focus_out(ViewController *view_controller, bool *is_focus_out) {
-	if (!*is_focus_out) {
-		*is_focus_out = true;
-		if (OS::get_singleton()->get_main_loop())
-			OS::get_singleton()->get_main_loop()->notification(
-					MainLoop::NOTIFICATION_WM_FOCUS_OUT);
-
-		[view_controller.view stopAnimation];
-		if (OS::get_singleton()->native_video_is_playing()) {
-			OSIPhone::get_singleton()->native_video_focus_out();
-		}
-
-		AudioDriverCoreAudio *audio = dynamic_cast<AudioDriverCoreAudio *>(AudioDriverCoreAudio::get_singleton());
-		if (audio)
-			audio->stop();
-	}
-}
-
-static void on_focus_in(ViewController *view_controller, bool *is_focus_out) {
-	if (*is_focus_out) {
-		*is_focus_out = false;
-		if (OS::get_singleton()->get_main_loop())
-			OS::get_singleton()->get_main_loop()->notification(
-					MainLoop::NOTIFICATION_WM_FOCUS_IN);
-
-		[view_controller.view startAnimation];
-		if (OSIPhone::get_singleton()->native_video_is_playing()) {
-			OSIPhone::get_singleton()->native_video_unpause();
-		}
-
-		AudioDriverCoreAudio *audio = dynamic_cast<AudioDriverCoreAudio *>(AudioDriverCoreAudio::get_singleton());
-		if (audio)
-			audio->start();
-	}
-}
-
 - (void)controllerWasConnected:(NSNotification *)notification {
 	// create our dictionary if we don't have one yet
 	if (ios_joysticks == nil) {