autorelay: refactor libp2p.EnableAutoRelay option

[MarcoPolo]

We should split the function into two options, one that requires a list of static relays and one that requires a peer source. Having options, some of which are required, is not a nice API pattern.

Originally posted by @marten-seemann in #1852 (comment)

[marten-seemann]

Suggestion: libp2p.EnableAutoRelayWithStaticRelays([]peer.AddrInfo) and libp2p.EnableAutoRelayWithAutoDiscovery(func(ctx context.Context, num int) <-chan peer.AddrInfo)?

I'd be grateful for better naming suggestions :)

[MarcoPolo]

Preference for libp2p.EnableAutoRelayWithPeerSource.

[p-shahi]

@sukunrt Flagging this for you in case you are interested in taking on more issues. Thanks for all the great contributions up till now, no pressure to take this up however 🙏

[sukunrt]

sure! I'd love to!

[sukunrt]

As I understand.

We want two new functions to configure autorelay

libp2p.EnableAutoRelayWithStaticRelays([]peer.AddrInfo, opts ...autorelay.Option)
libp2p.EnableAutoRelayWithPeerSource(func(ctx context.Context, numPeers int) <-chan peer.AddrInfo, opts ...autorelay.Option)

We would need to add the second options parameter because otherwise there would be no way of providing options like WithCircuitV1Support()

In autorelay.WithPeerSource there is a configurable mininterval for callbacks which is set to 30 seconds in autorelay.WithStaticRelays. Should I allow for setting this minInterval too and make the function:

libp2p.EnableAutoRelayWithPeerSource(func(ctx context.Context, numPeers int) <-chan peer.AddrInfo, minInterval time.Duration, opts ...autorelay.Option)

What should I do with the old function libp2p.EnableAutoRelay? Deprecate it or remove it?

[marten-seemann]

We want two new functions to configure autorelay

libp2p.EnableAutoRelayWithStaticRelays([]peer.AddrInfo, opts ...autorelay.Option)
libp2p.EnableAutoRelayWithPeerSource(func(ctx context.Context, numPeers int) <-chan peer.AddrInfo, opts ...autorelay.Option)

That's correct.

In autorelay.WithPeerSource there is a configurable mininterval for callbacks which is set to 30 seconds in autorelay.WithStaticRelays. Should I allow for setting this minInterval too and make the function:

libp2p.EnableAutoRelayWithPeerSource(func(ctx context.Context, numPeers int) <-chan peer.AddrInfo, minInterval time.Duration, opts ...autorelay.Option)

I'd prefer to have this as a autorelay.Option.

What should I do with the old function libp2p.EnableAutoRelay? Deprecate it or remove it?

If it's not too much of a hassle to keep it around (as a deprecated function), I'd say let's just deprecate it. That will make the upgrade process smoother for our users.

[sukunrt]

Can I change autorelay.WithPeerSource from

func WithPeerSource(f func(ctx context.Context, numPeers int) <-chan peer.AddrInfo, minInterval time.Duration) Option 

to

func WithPeerSource(f func(ctx context.Context, numPeers int) <-chan peer.AddrInfo) Option 

and set a default minInterval with autorelay.defaultConfig