feat(api): Implemented session closed and kick event via websocket (#87)

Reviewed-on: #87
Reviewed-by: lq64 <lq@blackhole.local>
Co-authored-by: Janis <janis.e.20@gmx.de>
Co-committed-by: Janis <janis.e.20@gmx.de>

knockoutwhistweb/app/util/mapper/LobbyUpdateEventMapper.scala

@@ -0,0 +1,25 @@
+package util.mapper
+
+import events.LobbyUpdateEvent
+import model.sessions.UserSession
+import play.api.libs.json.{JsArray, JsObject, Json}
+
+object LobbyUpdateEventMapper extends SimpleEventMapper[LobbyUpdateEvent] {
+
+  override def id: String = "LobbyUpdateEvent"
+
+  override def toJson(event: LobbyUpdateEvent, session: UserSession): JsObject = {
+    Json.obj(
+      "host" -> session.host,
+      "maxPlayers" -> session.gameLobby.maxPlayers,
+      "players" -> JsArray(session.gameLobby.getPlayers.values.map(player => {
+        Json.obj(
+          "id" -> player.id,
+          "name" -> player.name,
+          "self" -> (player.id == session.user.id)
+        )
+      }).toList)
+    )
+  }
+
+}