Function send_leader_change_and_set_flags 

fn send_leader_change_and_set_flags(
    is_leader: &AtomicBool,
    leader_infancy: &AtomicBool,
    tx: &Sender<LeaderChangeMessage>,
    msg: LeaderChangeMessage,
)

Sends a leader change message to the channel and sets the is_leader flag. If a leader is elected, it will also set the leader_infancy flag to true.