Adding graphics for Zero Gravity game

[MonikaSvata]

Description

Adding graphics for Zero Gravity game

Definition of Done

• Balance icon is added
• Graphics for astronaut poses for Zero Gravity game are added
• Check they are named appropriately in the zero gravity save data (the 'poseType' colum is the same as the sprite png name)

Dependencies

• #issue number

Comments

[MonikaSvata]

To be picked up after @K-Meech finishes with changes to Zero Gravity game.

[MonikaSvata]

@mmcleod89 to update with the latest graphics after @K-Meech merges her changes.