Add some new testcases to dialin and dialout mode

[MuLinForest]

• In gnmi_server/server_test.go Add getting queues tests and non-db data test. Since the non-db data could not be known in advance, so the return data is removed and it only compares with the path to verify.
  • TestGnmiGET:
    • Get COUNTERS:Ethernet68 Queues
    • Get COUNTERS (use vendor alias):Ethernet68/1 Queues
    • Get COUNTERS:Ethernet* Queues
    • get non-db platform cpu
  • TestGnmiSubscribe:
    • poll query for platform/cpu
• In dialout/dialout_client/dialout_client_test.go Add periodic report type test. The non-db response is verified by path. Therefore, I add a new function to compare the path.
  • DialOut to first collector in periodic mode (COUNTERS_PORT_NAME_MAP)
  • DialOut to first collector in periodic mode (COUNTERS/Ethernet*)
  • DialOut to second collector in periodic mode upon failure of first collector (COUNTERS/Ethernet68/Queues)
  • DialOut to second collector in periodic mode upon failure of first collector (platform/cpu)

[MuLinForest]

@hui-ma hi, could you please help to review