Ad-hoc collection for global and session based capturing

[hlubek]

It should be possible to configure Devlog to not collect anything by default.

We should consider 2 capture modes (exclusive):

• Global, can be toggled to collect all events via the UI with a button (which shows the capture state)
• Session-based, can be toggled to collect only events from the current session (for multiple users!)
  • We could set a cookie with a unique session UUID that will be used by the webapp and the collector to only enable collection (then also for nested events) if a HTTP server request with a Devlog session is sent
  • That way the dashboard can filter for top-level events of the current session
  • We need to think about how that affects limiting (maybe we need a hard-limit for collection and soft-limit for returning events in the dashboard endpoints)

[hlubek]

Idea:

We add generic labels to events, where collectors and custom code can contribte to the labels being collected.
A reverse index could be built to search by label.
A capture filter with label selector could be passed, so only these events should be captured.

[hlubek]

Implemented without generic labels but new architecture for collection, aggregation and storage per session in #7