dcutr: Remove ActionBuilder

[mxinden]

In libp2p-dcutr we introduced ActionBuilder as events from the ConnectionHandler could not be enriched with the local node's external addresses from the on_* event handlers. Instead, one had to wait for the NetworkBehaviour::poll method to access the addresses.

rust-libp2p/protocols/dcutr/src/behaviour_impl.rs

Lines 349 to 363 in 68d0f88

	/// A [`NetworkBehaviourAction`], either complete, or still requiring data from [`PollParameters`]
	/// before being returned in [`Behaviour::poll`].
	enum ActionBuilder {
	Done(NetworkBehaviourAction<Event, handler::Prototype>),
	Connect {
	attempt: u8,
	handler: NotifyHandler,
	peer_id: PeerId,
	},
	AcceptInboundConnect {
	inbound_connect: Box<protocol::inbound::PendingConnect>,
	handler: NotifyHandler,
	peer_id: PeerId,
	},
	}

Now that #3153 is merged, event handlers have access to the external addresses right away, thus the ActionBuilder abstraction is no longer needed. Let's remove it.

[thomaseizinger]

Done in #3304.