Keep previous resource taps and placements when restarting a level

[bilalakil]

When a player restarts a level by pressing R, either during the construction or combat phase, or after they win or lose the level, their previously placed maze and towers, and the resources they tapped to place them, should be pre-placed and tapped on the newly restarted level. This will allow them to more quickly refine their strategy instead of having to tap and place everything all over again, especially when larger or more complex defences are involved.

This will additionally require a simple way to reset all tapped / placed resources for a clean start, e.g. a button somewhere on the UI.

• Resource taps are kept after restarting by any means
• Structure placements are kept after restarting by any means
• The player can reset all taps and placements somehow