uikit: Send fullscreen enter/leave events

Send fullscreen enter/leave events, which will implicitly update the fullscreen flag. Manually setting the flag will suppress attempts to send the events later, as the flag is used for deduplication purposes in the event code.

src/video/uikit/SDL_uikitwindow.m

@@ -309,11 +309,7 @@ void UIKit_SetWindowBordered(SDL_VideoDevice *_this, SDL_Window *window, SDL_boo
 int UIKit_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_VideoDisplay *display, SDL_bool fullscreen)
 {
     @autoreleasepool {
-        if (fullscreen) {
-            window->flags |= SDL_WINDOW_FULLSCREEN;
-        } else {
-            window->flags &= ~SDL_WINDOW_FULLSCREEN;
-        }
+        SDL_SendWindowEvent(window, fullscreen ? SDL_EVENT_WINDOW_ENTER_FULLSCREEN : SDL_EVENT_WINDOW_LEAVE_FULLSCREEN, 0, 0);
         UIKit_UpdateWindowBorder(_this, window);
     }
     return 0;