Added possible moves indicators, tweaked hexSideLength

CheckersClient/android/assets/Game/1x/Possible_Field.png

...t/core/src/com/mygdx/game/controllers/GameController.java

CheckersClient/core/src/com/mygdx/game/controllers/Utils.kt

CheckersClient/core/src/com/mygdx/game/model/Game.kt

CheckersClient/core/src/com/mygdx/game/views/PlayView.java

...lient/core/src/com/mygdx/game/views/enums/PlayAssets.java