Add option to start new root span with link to remote context

[soluchok]

The problem: When we have hundreds of streams reading from the same NATS topic, traces in Jaeger are tied to a single root span.

The solution: This PR introduces a new option, new_root_span_with_link, which creates a new root span while preserving a link to the original span.

[jem-davies]

@soluchok - I see this PR is marked as draft - is it still being worked on?

The docs can be generated by running make docs - it is mentioned on the CONTRIBUTING.md file

[gregfurman]

Hey @soluchok 👋 Will give this a look a bit later today. Apologies for the delay.

[gregfurman]

LGTM 🤩 Thanks for the super neat addition!!

If possible, would love if we could add a test. Happy to do in a follow-up, or I can just push to your branch, given how long it's taken us to review this (we squash commits so PR will be solely authored to you).

[gregfurman]

Can we change tracingVersion here to v1.0.0 and your addition to v1.13.0 (the upcoming release)? Seems the tracingVersion is still referencing a pre-fork version that isn't relevant here 😃

[gregfurman]

suggestion: Let's add a Default of false here to allow no value being set to pass config validations.

[gregfurman]

Since this is a bool field, if we error out here you could just ignore the error since it'll default to false i.e

Suggested change

	newSpan, err := p.FieldBool(nrswlField)
	if err != nil && !strings.Contains(err.Error(), "was not found in the config") {
	return nil, err
	}
	newSpan, _ := p.FieldBool(nrswlField)
	if err != nil {
	return nil, err
	}

Properly configuring the config to have a default means this check would probably fall away. Else, since this is optional, we can add a p.Contains(nrswlField) and only do this check if the field exists in the parsed config

see example

bento/internal/httpclient/auth_oauth2.go

Lines 115 to 117 in f56fc96

	if !conf.Contains(aFieldOAuth2) {
	return
	}

and (probably incorrectly formatted) suggestion 👇

Suggested change

	newSpan, err := p.FieldBool(nrswlField)
	if err != nil && !strings.Contains(err.Error(), "was not found in the config") {
	return nil, err
	}
	var newSpan bool
	if p.Contains(nrswlField) {
	if err != nil {
	return nil, err
	}
	}

[gregfurman]

Hey @soluchok 👋 Do you no longer have have capacity to address my review? I opened a PR in your fork since I don't have permissions to push to your feature branch directly.

Otherwise, I'm happy to close this PR, cherry-pick your commit, and open another with the new changes included. Lmk!