Removes $resources and $markup class properties

[n7studios]

Summary

Removes code in the API class that stores the results of get_resources() and get_resource() functions into class properties.

This data isn't cached and doesn't persist beyond a single PHP request life cycle, so it's pointless.

If developers wish to cache the results of an API call (such as a list of forms or landing page HTML markup), they can do so within their application.

Testing

Existing tests pass.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

[noelherrick]

Makes sense.