add Panorama license check

[cdot65]

Checklist for This Pull Request

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• [x] Ensure you are submitting your pull request to a branch dedicated to a specific topic/feature/bugfix. Avoid using the master branch for pull requests.
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Pull Request Description

Implemented a check to validate that Panorama appliances are active in their licenses before upgrading. Our dependency of Upgrade Assurance package prevents us from running the readiness checks on Panorama appliances, so we have instead used the op method to perform request license info and perform validation on the response object.

The script will gracefully exit if there is no license info:

<response status="success">
    <result>
        <licenses></licenses>
    </result>
</response>

Or if the license entries are expired

<response status="success">
    <result>
        <licenses>
            <entry>
                <feature>Device Management License</feature>
                <description>VM Panorama license to manage up to 25 devices</description>
                <serial>0007EV12345</serial>
                <issued>February 03, 1999</issued>
                <expired>yes</expired>
                <authcode>I5012345</authcode>
            </entry>
            <entry>
                <feature>Premium</feature>
                <description>24 x 7 phone support; advanced replacement hardware service</description>
                <serial>0007EV48639</serial>
                <issued>February 03, 1999</issued>
                <expires>February 01, 2020</expires>
                <expired>yes</expired>
                <authcode>F2312345</authcode>
            </entry>
        </licenses>
    </result>
</response>

Otherwise the upgrade will continue.

What does this pull request accomplish?

• Feature addition

Are there any breaking changes included?

• [ ] Yes
• [x] No

Is there anything the reviewers should know?

Thank you for your contributions!