Play-test from a running game returns into the game

Stop brings the player back to the scene they were in instead of the main
menu, and a scene switch inside the played scenario ends the play-test in
place. New GUI test suite ingame_play covers both.

manifest.json

@@ -10,6 +10,7 @@
   ],
   "depends": ["dialog_base>=1", "interactive_base>=1", "time_base>=1", "map_base>=1", "ui_base>=1"],
   "test_suites": [
-    {"id": "windows", "activate": ["--itest=tools_windows"]}
+    {"id": "windows", "activate": ["--itest=tools_windows"]},
+    {"id": "ingame_play", "activate": ["--itest=ingame_play"]}
   ]
 }