support for multiple instances of openonu-go adapter

Support for multiple instances of the openonu adapter in go

the adapter should simply report a different topic for each replica:
https://github.com/opencord/voltha-openonu-adapter-go/blob/master/cmd/openonu-adapter/main.go#L290-L292
To support multiple openolt adapter we’ll also need to remove this config and read it from Endpoint manager: https://github.com/opencord/voltha-openonu-adapter-go/blob/master/internal/pkg/config/config.go#L44