[studio] Add admin user session management

[michaelvlach]

As users now have sessions admin of the server can do similar actions for the users:

1. Log all users out: (/api/v1/admin/user/logout_all)
2. Log out all user session: ('/api/v1/admin/user/{username}/logout`) - original endpoint, current behaviour
3. Log out user sessions: (/api/v1/admin/user/{username}/logout?session={session}) - where {session} is the identifier from the UserStatus

Similarly to /user/status the /admin/user/list also has the list of sessions for each user:

export interface UserStatus {
    admin: boolean;
    login: boolean;
    sessions: UserSession[];
    username: string;
}