Initial commit of estimator component

[rgeyer]

PR Description

Adds a new component for estimating/reporting the "amount" of a given billable unit is being received.

For metrics, the number of active series.
For logs and traces, the byte throughput/counter.

The component will also expose a prometheus exporter interface, and a list of targets which can be scraped and remote written for analysis.

Notes to the Reviewer

PR Checklist

• CHANGELOG updated
• Documentation added
• Tests updated

[cyriltovena]

Suggested change

	metricsReceiver *prometheus.Interceptor `river:metrics_reciever,attr`
	metricsReceiver *prometheus.Interceptor `river:metrics_receiver,attr`

[rgeyer]

Spelling is hard 😂

This is getting refactored anyhow, but, I have fixed the spelling :)

[tpaschalis]

Hey there @rgeyer 👋

Do you think we should make a push for including these new components (adding documentations, tidying code up etc), or was it more of a proof of concept?

I'm going through a round of tidying up our PR queue and was thinking of closing this otherwise.

[rgeyer]

Hey there @rgeyer 👋

Do you think we should make a push for including these new components (adding documentations, tidying code up etc), or was it more of a proof of concept?

I'm going through a round of tidying up our PR queue and was thinking of closing this otherwise.

Only the metrics portion was "correct". The logging functionality is incorrect, and I'm not sure I'd be able to resolve it.

That said, the work that @captncraig did for the most recent hackathon (x-ray), I think this becomes superflous. Also, x-ray seems more complete and useful.

I think we can close this.