/// <summary>
/// Adds a user to the application. Sends a list of all active users to the frontend
/// </summary>
/// <param name="user">User to be added</param>
/// <returns></returns>
public async Task AddUser(User user)
{
var connectionId = Context.ConnectionId;
user.ConnectionId = connectionId;
_users.Add(connectionId, user);
await Clients.All.SendAsync("addUser", _users.GetUsers());
}