GUI: reworked GUI to support non-blocking UI:

- GUI: added non-blocking UI to almost all app and game dialogs;
- GUI: it allows to switch between UI dialogs and use any UI elements at any moment;
- GUI: it allows to use chat, card popup, battlefield, concede and other features while choosing (related to #12670);
- GUI: it allows to download images while playing (related to #4160, not fully tested);
- GUI: enabled by default, can be disabled by java option: -Dxmage.guiModalMode=true
- connection: auto-connect will be visible in main menu on startup;
- connection: removed some unused features (auto-connect by command line);
- connection: added <ESC> button to close connection dialog;
- download: added background images download (see non-blocking UI);
- download: improved cancel stability and fixes that it can't stop preparing/downloading process in some use cases;
- app: fixed freezes on macOS systems in some use cases (related to #12431, #11292, #9300, #4920);

Mage.Common/src/main/java/mage/view/UserRequestMessage.java

@@ -6,7 +6,7 @@ import java.io.Serializable;
 import java.util.UUID;
 
 /**
- * GUI: settings for message window that allows to choose additional action (can be used in game or outside)
+ * App GUI: settings for message window that allows to choose additional action (can be used in game or outside)
  *
  * @author LevelX2
  */