public enum Invitation
Defines how the multipeer connection handles newly discovered peers. New peers can be invited automatically, invited with a custom context and timeout, or not invited at all, in which case you must invite them manually.
.automatic is used, all found peers will be immediately invited to join the session.
case custom(: (Peer) throws -> (context: Data, timeout: TimeInterval)?)
.custom when you want to control the invitation of new peers to your session,
but still invite them at the time of discovery.
.none when you want to manually invite peers by calling