Fix broken APK expansion due to missed option renames

Command line options were refactored for 3.0 to follow the common usage
of double-dashed long options, but `--main-pack` went through the cracks.

Fixes #16533.

platform/android/java/src/org/godotengine/godot/Godot.java

@@ -404,7 +404,7 @@ public class Godot extends Activity implements SensorEventListener, IDownloaderC
 				new_cmdline = new String[2];
 			}
 
-			new_cmdline[cll] = "--main_pack";
+			new_cmdline[cll] = "--main-pack";
 			new_cmdline[cll + 1] = expansion_pack_path;
 			command_line = new_cmdline;
 		}