Credentials enhancement with ssh key use

[AlanKane640]

Environment

• Nautobot version: *
• nautobot-device-onboarding version: *

Proposed Functionality

Connecting to devices using ssh key.

Use Case

The user should have the choice to use ssh key to connect to devices either by using Nautobot secret key or by specifying NAPALM options in a new form field (JSON format).

Thanks.