IPVGO: Support scripts playing against each other as each color on "No AI" boards (#1917)

This is a big change with a *lot* of moving parts.

The largest part of it is enabling scripts to `playAsWhite` as a parameter to many Go functions. In the implementation, this involved a significant rewrite of `opponentNextTurn` promise handling.

A number of other changes and bugfixes are included:
* Fixes the issue where handicap stones are added on game load.
* Better typing for error callbacks.
* Throw errors instead of deadlocking on bad cheat usage.
* Return always-resolved gameOver promise after game end
* Added a new `resetStats` api function.

---------

Co-authored-by: David Walker <d0sboots@gmail.com>

test/jest/__snapshots__/FullSave.test.ts.snap

@@ -40,7 +40,9 @@ exports[`Check Save File Continuity GoSave continuity 1`] = `
       ".......",
     ],
     "cheatCount": 0,
+    "cheatCountForWhite": 0,
     "passCount": 0,
+    "previousBoard": "",
     "previousPlayer": "White",
   },
   "previousGame": null,