Offline Caching Support

[HazAT]

Like in other SDKs
https://docs.sentry.io/platforms/java/configuration/#configuring-offline-caching

[timfish]

This is likely required to support this:

• Transport send_envelope should return a Result  #482

[pronebird]

This is a huge blocker for adoption for me since most of errors I encounter happen when there is no connectivity. Is there any estimate on when this could be included in the Rust SDK?

[lcian]

@pronebird We don't have a timeline for when we'll work on this, but it helps us to know that it's something you might benefit from, we just didn't have many users asking for this yet.
On a side note, as I saw you recently started using it in your Rust service, we've just released logs support for the tracing integration, you might be interested in enabling it.