Creating a new device with type plugin just returns a normal device

Creating a new device with the flag type plugin creates a normal openconfig device.

Description

As the TODO (here) suggests it is currently only working with cSBI and not with plugins. Because the manifest file is not provided while requesting a plugin.

Expected Behavior

A new Csbi Device should be returned with SouthboundPlugin as SBI.

Actual Behavior

A standard openconfig device is returned.

Possible Fix

Steps to Reproduce

1. Create a new device via gosdnc with type plugin

Context

Your Environment

• Version used:
• Environment name and version (e.g. go v1.16.3 on FreeBSD 13.0-current):
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• Operating System and version: