feat: Implementation of a relay manager

[dariusc93]

This PR introduce a relay manager crate at the aim of being a rewrite of libp2p-autorelay with the means of simplifying the logic.

Note:

• This will not utilize any autorelay selection at this time
• Does not check over DHT for any relays (largely due to determining the best course besides emitting an event with a channel)

Reference:

• Auto relay connection #4