Keepalive on grpc connections

[LionelJouin]

Description

Add keepalive setting for grpc connections towards NSP and IPAM improving the time for connection to be re-established after a failure.

https://www.evanjones.ca/tcp-connection-timeouts.html

Issue link

#355

Checklist

• Purpose
  • Bug fix
  • New functionality
  • Documentation
  • Refactoring
  • CI
• Test
  • Unit test
  • E2E Test
  • Tested manually
• Introduce a breaking change
  • Yes (description required)
  • No

[LionelJouin]

{"severity":"error","timestamp":"2023-04-24T16:03:03.865+00:00","service_id":"Meridio-ipam","message":"watchConduitClient.Recv","version":"1.0.0","extra_data":{"class":"ConduitWatcher","error":"rpc error: code = Unavailable desc = closing transport due to: connection error: desc = \"error reading from server: EOF\", received prior goaway: code: ENHANCE_YOUR_CALM, debug data: \"too_many_pings\""}}