[elixir] Support for "Metrics"

[smeubank]

Description

Metrics! Sentry will support Metrics finally! First we need all of our SDKs to support Metrics, including the Elixir SDK

Requirements:

• API for sending Metrics
• Metrics Summary
• Code location
• Tag normalization

Document(s)

Develop Specs
SDK Develop Specs
Product Specs

[whatyouhide]

For now, we're not actively working on this in this SDK, waiting for a few cycles here.

[smeubank]

@whatyouhide hi, yes that is fine :D

the naming is a project convenience for me, as i track this across all SDKs and the GH timeline board with multi-repo makes it difficult to see which SDK is which in the view

so you could you please leave the [elixir] prefix to make my life easier

[whatyouhide]

Ah yes sure my bad 👍

[grantwest]

Any idea on when this work might happen?

[whatyouhide]

Deferring to @sl0thentr0py and @stephanie-anderson for this 🤓

[HazAT]

We going to revisit this plan, currently the idea is that Metrics are just attributes on a Span. So, as described in the initial comment, it for sure is not gonna happen like this.