Graceful disconnect

[mhelleborg]

Summary

Adds graceful disconnects for event handlers. This ensures that the system waits for the current handlers to complete before completing shutdowns / disconnects.

Also adresses some minor internal fixes.

Changed

• Updated projections to accommodate newer MongoDB drivers.
• Rewritten event handlers to support graceful disconnects from the client.

Fixed

• Resolved an issue in eventlogstream-subscriptions, ensuring correct subscription cancellation.

[TomasEkeli]

let's get it out and try it out!