Add CRUD APIs for Templates and Strategic Groups

It is suggested by Netreo to use Templates to assign credentials to Strategic Groups that are applied to devices. However, there are no API landings to handle these first two steps.

This forces automated onboarding efforts to use the two different device related landings to set SNMP and SSH credentials directly on devices instead of using templates. You can assign them by other means, but you cannot create them.

I have worked around this by doing programmatic form submissions, but that is not ideal, as there is frontend validation that is not (or was not at the time) applied to the backend which has caused issues in the past.