Investigate existing solutions to speed up Local Hub rewrite

[pkosiec]

Description

Before implementing #605, investigate existing libraries and tools to speed-up Local Hub development, which should use PostgreSQL.

• Consider https://github.com/dosco/graphjin (try it as first)
  • Look for Go alternatives
  • Prepare PoC
• If it is good enough, end investigation
• If it miss some features, try out Node.js alternatives

Additional scope

After initial investigation:

• Reevaluate dgraph as Neo4j replacement for Local (and Public) Hub

Related issues

See epic #604 for reason and use cases.