[Feature request] Implement roll back to previous phase

I would like to implement this roll back feature, but I'm having trouble understand how the modules interact with each other
to achieve normal roll back.

The "previous phase roll back" should work like this: during the two Main phases the state of the game is saved. When the player misplay (for example in the combat phase) he/she can trigger the "Previous phase roll back" to restore the Main phase (that will be the pre or post combat w.r.t the current phase).

Start by tracing how the game modules implement normal rollback and how state is saved during the two Main phases. Define the pre- or post-combat Main-phase state that should be restored, then verify that a player-triggered rollback returns the game to that state.

Written by the indexing model from the issue text.