exporter: Prometheus Remote Write API

[eraac]

closes #122

It's the first time I wrote Python code, there are probably a lot to say/review.

• I've made a separate exporter but maybe it's better to add to the current prometheus exporter?
• proto file is directly in slo_generator/exporters/ but maybe there a better path for it?
• I'm not sure where I can add documentation about protobuf compilation

Concerning the .proto, I've copy the one from prometheus repository, and removing unnecessary element

Thanks!

[oktocat]

loool we're doing the same thing #177
how do you want to go about it?

[eraac]

loool we're doing the same thing #177 how do you want to go about it?

What are the odds? But I think there are no discussion about which one is better 😅

[oktocat]

loool we're doing the same thing #177 how do you want to go about it?

What are the odds? But I think there are no discussion about which one is better sweat_smile

so, what do we do now? :)
I'll need a day or two to write all the tests and docs. Want to help?

[eraac]

I close this one and merging our efforts into #177