a11y: Output which cells changed when the Player moves

[philschatz]

Sometimes other things move when the player presses up/down/left/right/action. For example, a cat might follow the player. In those cases it would be good to tell non-sighted users that the player was unable to move and if other sprites also moved (or were created/removed).

For example:

1. Pressing Right next to a wall might say Player did not move
2. Pressing Up might say Cat moved UP (the player also moved but that is assumed)

It might be easier to implement #50 before implementing this since that work will monitor to see when sprites change