Record player deaths (#2102)

## Description:

Record player death ticks and "conquests" (when a player has < 100
tiles).
Tournaments would be easier to manage with those information.

Related infra PR: https://github.com/openfrontio/infra/pull/196

Tested locally with docker/infra repo

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

IngloriousTom

src/core/game/Stats.ts

@@ -93,4 +93,7 @@ export interface Stats {
 
   // Player loses a unit of type
   unitLose(player: Player, type: OtherUnitType): void;
+
+  // player was killed (0 tiles)
+  playerKilled(player: Player, tick: number): void;
 }

src/core/game/StatsImpl.ts

@@ -133,6 +133,22 @@ export class StatsImpl implements Stats {
     p.units[type][index] += _bigint(value);
   }
 
+  private _addConquest(player: Player) {
+    const p = this._makePlayerStats(player);
+    if (p === undefined) return;
+    if (p.conquests === undefined) {
+      p.conquests = _bigint(1);
+    } else {
+      p.conquests += _bigint(1);
+    }
+  }
+
+  private _addPlayerKilled(player: Player, tick: number) {
+    const p = this._makePlayerStats(player);
+    if (p === undefined) return;
+    p.killedAt = _bigint(tick);
+  }
+
   attack(
     player: Player,
     target: Player | TerraNullius,
@@ -225,6 +241,7 @@ export class StatsImpl implements Stats {
 
   goldWar(player: Player, captured: Player, gold: BigIntLike): void {
     this._addGold(player, GOLD_INDEX_WAR, gold);
+    this._addConquest(player);
   }
 
   unitBuild(player: Player, type: OtherUnitType): void {
@@ -246,4 +263,8 @@ export class StatsImpl implements Stats {
   unitLose(player: Player, type: OtherUnitType): void {
     this._addOtherUnit(player, type, OTHER_INDEX_LOST, 1);
   }
+
+  playerKilled(player: Player, tick: number): void {
+    this._addPlayerKilled(player, tick);
+  }
 }