Support for Traces/Transactions via Opentelemetry

[solnic]

This adds support for Traces via Opentelemetry integration, handled by our custom Sentry.Opentelemetry.SpanProcessor which accumulates spans and turns them into hierarchical transactions that are then sent to Sentry.

For this to work the following deps must be added to an app:

{:opentelemetry, "~> 1.4"},
{:opentelemetry_api, "~> 1.3"}

Furthermore, Opentelemetry needs to be configured with our SpanProcessor:

config :opentelemetry, span_processor: {Sentry.Opentelemetry.SpanProcessor, []}

The rest will automagically work.

Supported opentelemetry packages

This initial implementation supports the following Opentelemetry packages:

• opentelemetry_phoenix
• opentelemetry_bandit
• opentelemetry_ecto
• opentelemetry_oban

Considerations

• Should we add new deps as sentry deps instead of having people add them manually to their mix.exs?
• Would it make sense to try to pre-configure opentelemetry automatically?
• Which other opentelemetry_* packages do we want to support initially?
• Should we support top-level ecto events that occur when ie Ecto tries to create migrations table, or checks migrations? (I think we should ignore them, FWIW)

[whatyouhide]

@solnic can you rebase this one now that #797 has been merged? Gonna make it easier to review I think 😄

[solnic]

@solnic can you rebase this one now that #797 has been merged? Gonna make it easier to review I think 😄

@whatyouhide done!

[solnic]

I've split this into #842 and #843 /cc @whatyouhide

[grantwest]

I've split this into #842 and #843 /cc @whatyouhide

Does that mean this PR will be closed without merging?

[solnic]

I've split this into #842 and #843 /cc @whatyouhide

Does that mean this PR will be closed without merging?

Depending on which one is simpler to review, to be honest. I can of course rework this one on top of #842 but this is the 50th comment here so maybe we'd benefit from a cleaner slate. WDYT @whatyouhide?