Knowledge base import should support Hubspot's own knowledge base export

[DBolton4]

If I export the knowledge base from Hubspot then reimport it I would expect the import to work. Unfortunately it does not (due to the error "some categories couldn't be imported" on every article.

My reason for exporting and reimporting was to try and fix issues across all articles (using find and replace). Instead we spent several days manually fixing each article individually.