[FEATURE] Add possibility to scale up PostgreSQL cluster

[plirglo]

Is your feature request related to a problem? Please describe. Currently Epiphany does not support scaling up of PostgreSQL cluster. I think we should consider to add such option in v2.0

Describe the solution you'd like Changing the number of PostgreSQL nodes extending database cluster without losing any database data

Additional context We need to save working state and use it before cluster extension to avoid:

• node_id duplication in repmgr
• cluster re-creation while running apply

Scaling down is not require

---

DoD checklist

• Changelog
  • [ ] updated
  • [ ] not needed
• COMPONENTS.md
  • [ ] updated
  • [ ] not needed
• Schema
  • [ ] updated
  • [ ] not needed
• Backport tasks
  • [ ] created
  • [ ] not needed
• Documentation
  • [ ] added
  • [ ] updated
  • [ ] not needed
• [ ] Feature has automated tests
• [ ] Automated tests passed (QA pipelines)
  • [ ] apply
  • [ ] upgrade
  • [ ] backup/restore
• [ ] Idempotency tested
• [ ] All conversations in PR resolved
• [ ] Solution meets requirements and is done according to design doc
• [ ] Usage compliant with license