Reduced number of transactions within the outbox executor

[zaychenko-sergei]

Description

Outbox main loop was revised to minimize the number of transactions:

• split outbox into planner and consumption jobs
• planner analyzes current state and loads bunch of unprocessed messages within a 1 transaction ony
• consumption jobs invoke consumers and detect their failures

Checklist before requesting a review

• [x] Unit and integration tests added
• [x] Compatibility:
  • [x] Network APIs: ✅
  • [x] Workspace layout and metadata: ✅
  • [x] Configuration: ✅
  • [ ] Container images: ✅
• [ ] Documentation:
  • [x] Changelog: ✅
  • [ ] Public documentation: ✅
• [ ] Downstream effects:
  • [ ] kamu-node: ✅