Detect Conflicts with Custom Page Builder Appearances

[mpchadwick]

This will be tricky and not super high priority, but tracking here as it did come up recently

We had implemented a custom <appearance> for the row content_type. In 2.3.5, the Magento updated the appearance with some new XML to support video background images for rows. That caused our <appearance> to break and required porting over the new XML

[mpchadwick]

I think if it detects a modification to pagebuilder/content_type/*.xml and finds the same path not in vendor/magento it can report it