feat: Track Sessions for each request

[Swatinem]

This will create a new sentry session for each symbolication task, and flag that as abnormal in case it hits a timeout. Otherwise sessions will be closed when the hub/future they were created on is dropped.

[flub]

I'm not really sure what changed since last review? It still would seem more normal to me if the session was explicitly terminated in the same place for all cases taking care of ensuring the session is errored when needed.

[jan-auer]

In symbolicator, we have to tweak the meaning of our session statuses:

• "crashed" can be seen as fatal errors, where we're not able to deliver a symbolication result due to a severe issue. This is if we fail I/O locally, if the task times out, or if the task is killed.
• "errored" should be around problems with the payload and potentially also when required symbols fail to compute.
• Everything else can be OK.

[flub]

In symbolicator, we have to tweak the meaning of our session statuses:

• "crashed" can be seen as fatal errors, where we're not able to deliver a symbolication result due to a severe issue. This is if we fail I/O locally, if the task times out, or if the task is killed.
• "errored" should be around problems with the payload and potentially also when required symbols fail to compute.
• Everything else can be OK.

So does this PR implement this currently?

[Swatinem]

So does this PR implement this currently?

It should, yes. Things are marked as crashed on those conditions, otherwise the errored flag depends on ingesting error events during a sessions lifetime, so that should be the case as well.

[flub]

Apologies, I need a bigger redder flag on my screen saying i have unfinished reviews. LGTM!