Added "firstInput" stat and repurposed the "fileCreatedAt" stat. (#6070)

- The "firstInput" stat is set on first input in game. Used for RTA
  Timing.
- The "fileCreatedAt" stat is now set when then save file is created
  (After the player is done entering the file name). Useful for seeding
  non rando randomizers like Mirrorworld, Enemy Randomizer, extraTraps,
  etc.

soh/src/code/z_play.c

@@ -781,10 +781,10 @@ void Play_Update(PlayState* play) {
             }
 
             // Start RTA timing on first non-c-up input after intro cutscene
-            if (!gSaveContext.ship.stats.fileCreatedAt && !Player_InCsMode(play) &&
+            if (!gSaveContext.ship.stats.firstInput && !Player_InCsMode(play) &&
                 ((input[0].press.button && input[0].press.button != 0x8) || input[0].rel.stick_x != 0 ||
                  input[0].rel.stick_y != 0)) {
-                gSaveContext.ship.stats.fileCreatedAt = GetUnixTimestamp();
+                gSaveContext.ship.stats.firstInput = GetUnixTimestamp();
             }
         }
         // #endregion