Monitoring client connections (#941)

## Description:
Disconnected client detection :
If a client haven't send a ping to the server since more than 30 seconds
They will then be marked disconnected with a dedicated icon.
No action are yet taken, this allows for extensive in-game test before
adding the *consequences* of the player leaving the game.
I also added extensive unit tests, lessening the risk of regression for
the future.


![image](https://github.com/user-attachments/assets/884e5e99-15e8-4544-bd52-7524542cc82a)



## 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
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

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

---------

Co-authored-by: evanpelle <evanpelle@gmail.com>

src/core/game/Game.ts

@@ -433,6 +433,9 @@ export interface Player {
   largestClusterBoundingBox: { min: Cell; max: Cell } | null;
   lastTileChange(): Tick;
 
+  isDisconnected(): boolean;
+  markDisconnected(isDisconnected: boolean): void;
+
   hasSpawned(): boolean;
   setHasSpawned(hasSpawned: boolean): void;
 

src/core/game/GameUpdates.ts

@@ -103,6 +103,7 @@ export interface PlayerUpdate {
   smallID: number;
   playerType: PlayerType;
   isAlive: boolean;
+  isDisconnected: boolean;
   tilesOwned: number;
   gold: Gold;
   population: number;

src/core/game/GameView.ts

@@ -289,6 +289,9 @@ export class PlayerView {
   hasSpawned(): boolean {
     return this.data.hasSpawned;
   }
+  isDisconnected(): boolean {
+    return this.data.isDisconnected;
+  }
 }
 
 export class GameView implements GameMap {

src/core/game/PlayerImpl.ts

@@ -98,6 +98,7 @@ export class PlayerImpl implements Player {
   public _outgoingLandAttacks: Attack[] = [];
 
   private _hasSpawned = false;
+  private _isDisconnected = false;
 
   constructor(
     private mg: GameImpl,
@@ -135,6 +136,7 @@ export class PlayerImpl implements Player {
       smallID: this.smallID(),
       playerType: this.type(),
       isAlive: this.isAlive(),
+      isDisconnected: this.isDisconnected(),
       tilesOwned: this.numTilesOwned(),
       gold: this._gold,
       population: this.population(),
@@ -919,6 +921,14 @@ export class PlayerImpl implements Player {
     return this._lastTileChange;
   }
 
+  isDisconnected(): boolean {
+    return this._isDisconnected;
+  }
+
+  markDisconnected(isDisconnected: boolean): void {
+    this._isDisconnected = isDisconnected;
+  }
+
   hash(): number {
     return (
       simpleHash(this.id()) * (this.population() + this.numTilesOwned()) +