Validate spawn tile (#1512)

## Description:

Enforce valid tile during spawn, to prevent the game from crashing for
all players.

## 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
- [ ] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [ ] I have read and accepted the CLA aggreement (only required once).

src/client/graphics/layers/BuildMenu.ts

@@ -15,7 +15,6 @@ import { translateText } from "../../../client/Utils";
 import { EventBus } from "../../../core/EventBus";
 import {
   BuildableUnit,
-  Cell,
   Gold,
   PlayerActions,
   UnitType,
@@ -396,12 +395,7 @@ export class BuildMenu extends LitElement implements Layer {
         ),
       );
     } else if (buildableUnit.canBuild) {
-      this.eventBus.emit(
-        new BuildUnitIntentEvent(
-          buildableUnit.type,
-          new Cell(this.game.x(tile), this.game.y(tile)),
-        ),
-      );
+      this.eventBus.emit(new BuildUnitIntentEvent(buildableUnit.type, tile));
     }
     this.hideMenu();
   }

src/client/graphics/layers/PlayerActionHandler.ts

@@ -1,5 +1,5 @@
 import { EventBus } from "../../../core/EventBus";
-import { Cell, PlayerActions, PlayerID } from "../../../core/game/Game";
+import { PlayerActions, PlayerID } from "../../../core/game/Game";
 import { TileRef } from "../../../core/game/GameMap";
 import { PlayerView } from "../../../core/game/GameView";
 import {
@@ -61,8 +61,9 @@ export class PlayerActionHandler {
   ): Promise<TileRef | false> {
     return await player.bestTransportShipSpawn(tile);
   }
-  handleSpawn(spawnCell: Cell) {
-    this.eventBus.emit(new SendSpawnIntentEvent(spawnCell));
+
+  handleSpawn(tile: TileRef) {
+    this.eventBus.emit(new SendSpawnIntentEvent(tile));
   }
 
   handleAllianceRequest(player: PlayerView, recipient: PlayerView) {

src/client/graphics/layers/RadialMenuElements.ts

@@ -1,10 +1,5 @@
 import { Config } from "../../../core/configuration/Config";
-import {
-  AllPlayers,
-  Cell,
-  PlayerActions,
-  UnitType,
-} from "../../../core/game/Game";
+import { AllPlayers, PlayerActions, UnitType } from "../../../core/game/Game";
 import { TileRef } from "../../../core/game/GameMap";
 import { GameView, PlayerView } from "../../../core/game/GameView";
 import { flattenedEmojiTable } from "../../../core/Util";
@@ -427,11 +422,7 @@ export const centerButtonElement: CenterButtonElement = {
   },
   action: (params: MenuElementParams) => {
     if (params.game.inSpawnPhase()) {
-      const cell = new Cell(
-        params.game.x(params.tile),
-        params.game.y(params.tile),
-      );
-      params.playerActionHandler.handleSpawn(cell);
+      params.playerActionHandler.handleSpawn(params.tile);
     } else {
       params.playerActionHandler.handleAttack(
         params.myPlayer,