Remove Cheats/ExtraCheats distinction

It is not necessary as there is no longer a need to preserve
the size/order of struct Cheats

src/station_cmd.cpp

@@ -799,7 +799,7 @@ static CommandCost BuildStationPart(Station **st, DoCommandFlag flags, bool reus
 					ZoningTownAuthorityRatingChange();
 				}
 				SetBit((*st)->town->have_ratings, _current_company);
-				if (_extra_cheats.town_rating.value) {
+				if (_cheats.town_rating.value) {
 					(*st)->town->ratings[_current_company] = RATING_MAXIMUM;
 				}
 			}