Added ability to set the variablesr equired to load a cert

[usscarter]

The import module lacks the ability to define the variables that would be required to load a certificate to the firewall.

I added the settings required to load a certificate to the firewall, and identified the possible choices for the category that is able to be used as far as I was able to tell.

Motivation and Context

I could not load a SSL certificate to my firewall, which was kind of a big deal for automated deployments.

How Has This Been Tested?

I ran through testing in our lab environment, and tested it there.

Screenshots (if appropriate)

Types of changes

New code added

• New feature (non-breaking change which adds functionality)

Checklist

• [ ] I have updated the documentation accordingly.
• [ X] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes if appropriate.
• [ ] All new and existing tests passed.

[shinmog]

@usscarter

New feature development has halted for the Ansible Galaxy role and we are transitioning over to the Ansible collection instead. If you would, could you open a new PR against the collection's develop with this fix?

https://github.com/PaloAltoNetworks/pan-os-ansible