Support multiple STIGs per checklist

[stevehose]

Is your feature request related to a problem? Please describe.
Currently, creating a checklist is limited to one STIG per target.

Describe the solution you'd like
It is common to apply compound configurations that include multiple STIGs per target. Ideally, a checklist could be generated for a target that included all of the STIGs applicable to the target.

Describe alternatives you've considered
The only alternative is to manually combine checklist data. This defeats the purpose of automation.

[stevehose]

This is in the 4.4 release and will continue in future releases.