A requested Device via gRPC is missing SBI

The following discussion from !238 (merged) should be addressed:

• @istmabauc started a discussion: (+2 comments)

  In this case, the return of the corresponding SBI is missing. A simple fix should be the following:

  		onds[i] = &ppb.OrchestratedNetworkingDevice{
  			Id:     id,
  			Name:   d.Name(),
  			Device: dev,
  			Sbi: &spb.SouthboundInterface{
  				Id:   d.SBI().ID().String(),
  				Type: d.SBI().Type(),
  		}

  However, we should probably reconsider where we always want to return whole objects (be it PNDs, SBIs, etc.), as in some cases simply an ID might be enough.

• @istmabauc started a discussion:

  The copied device is not complete. This would cause problems with my suggestion in !238 (comment 229627).

  	copiedDevice := &CommonDevice{name: d.Name(), UUID: d.ID(), GoStruct: copiedGoStruct, sbi: d.SBI()}

  I'm not quite sure why we copy the device here. However, this is a topic for a new issue.