[finishes #73562792]: use minWorkspaceHeight, respace blocks, replace farmer PNGs

Improves bounce levels 9 and 10 (11 and 12 internally) using a technique adapted from studio.

minWorkspaceHeight allows us to grow the workspace height on a per-level basis.

Also removed the farmer PNGs from the bounce skin. Replaced most with the image from ball.png. Deleted avatar.png since it is not needed.