Use CancelWithCause in swarm.dialPeer for better metrics reporting

[sukunrt]

By using https://pkg.go.dev/context#CancelCauseFunc in swarm.dialPeer we can detect if we cancelled because we received a connection while tracking metrics. This will help us understand if we are cancelling because we received a connection or because the caller cancelled the call for some reason.

Since this type is not available in go 1.19 we might have to wait till go1.21 to tackle this.

[marten-seemann]

This is unblocked now, since we switched to Go 1.20. @sukunrt, should we get this into the v0.31 release?

[sukunrt]

Yeah, it'd be nice to get this in. Thanks for the reminder. I've raise a PR.