nInput_Init ssh key support

[nmaguiar]

Is your feature request related to a problem? Please describe.
The current nInput_Init support SSH entries with "idkey" pointing to the private key file. It would be nice to also support having the private key text directly in a secret or similar.

Describe the solution you'd like
It should be possible, like with OpenAF's $ssh, to have a field "id" to do the same as "idkey" and a field "key" with the private key text.

Describe alternatives you've considered
n/a

Additional context
n/a