Implement basic menu UI

[rdpolarity]

note: You don't have to decorate/style the menu and UI. We can create pixel art for it in another ticket. AC#1

• Create a main menu scene
• Create a 'play' button that sends you into the game
• Create a 'quit' button that stops the game
• Create a 'options' button which does nothing (for now)

AC#2

• Show a UI when the user hits the 'esc' key
• Create a 'main menu' button that sends the player back to the main menu
• Create a 'quit' button that stops the game
• Create a 'options' button which does nothing (for now)