Add display abstraction

In case we want to run this on something that isn't an ANSI terminal, we
have the option to implement it however we want.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

agame/action.py

@@ -13,6 +13,7 @@ __all__ = (
     "PrintAction",
     "PrintRoomAction",
     "PlayerInputAction",
+    "WaitForAckAction",
     "TeleportAction",
     "GetAction",
     "CheckInvItemsAction",
@@ -91,11 +92,10 @@ class PlayerInputAction(Action):
     Waits for a user to press a key, or press enter, or whatever.
     """
 
-    prompt: str = "Press enter to continue..."
     store_var_id: Optional[str] = None
 
     def act(self, game: "Game"):
-        line = input(self.prompt)
+        line = game.display.input()
         if self.store_var_id:
             assert (
                 self.store_var_id in game.vars
@@ -103,6 +103,18 @@ class PlayerInputAction(Action):
             game.vars[self.store_var_id] = line
 
 
+class WaitForAckAction(Action):
+    """
+    Waits for a player to press a single key, or press enter, to acknowledge and
+    continue processing.
+
+    This is basically "press any key to continue..." territory.
+    """
+
+    def act(self, game: "Game"):
+        game.display.wait_for_ack()
+
+
 @dataclasses.dataclass
 class TeleportAction(Action):
     """