[prometheusremotewritereceiver] add exponential histograms datapoints

[perebaj]

Description

This PR partially implements the native histograms from prometheus v2 to the Otel exponential histograms. For now, it's missing some implementations that I take care on a next PR. Like:

• Deal with scale
• Deal with positive and negative spans
• Maybe exemplars (I'm think that we can deal with exemplars in a next PR)
• Deal with positive and negative buckets

Link to tracking issue

Related to #37277

[perebaj]

Would appreciate the review from @carrieedwards @krajorama @ywwg and @ArthurSens

[perebaj]

Guys in the section prometheus metric points -> OLTP we just have a documentation talking about histograms. Should there be something talking about native histograms -> exponential histograms?

[krajorama]

Nice start, however I've added some comments on high level.

[ArthurSens]

I spent a very decent amount of time trying to review this PR and I feel like I don't have the necessary knowledge to do a decent review.

If @krajorama or @carrieedwards could do this for me so we can unblock your work, I'd be super grateful. In the meantime, I'll read up Carrie's document to learn more about this kind of histograms

[perebaj]

I spent a very decent amount of time trying to review this PR and I feel like I don't have the necessary knowledge to do a decent review.

If @krajorama or @carrieedwards could do this for me so we can unblock your work, I'd be super grateful. In the meantime, I'll read up Carrie's document to learn more about this kind of histograms

Nice, Carry docs plus the krajo implementation here is the way!

[krajorama]

I've left a couple of comments , should be close now.

[krajorama]

The conversion LGTM.

I've tried testing with source->prometheus->otel collector->mimir , but had some issues around handling unsupported types (summary, classic histogram) which meant I couldn't test end to end, but the debug exporter showed that the conversion is ok.

Incidentally the debug exporter crashed for me consistently even without native histograms , so there's more to be fixed for sure.

[ArthurSens]

Thanks for the patience while working on this one, it sure wasn't easy :)