Broadcasts: Import Images

[n7studios]

Summary

Adds this requested feature by including an option to save a Broadcast's images to WordPress when importing the Broadcast to a WordPress Post.

This won't import non-creator uploaded images, such as icons for links and social links.

Testing

• testBroadcastsImportWithImportImagesEnabled: Tests that Broadcasts import with inline images copied to WordPress when the Import Images option is enabled.

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)