Update find_or_create for extension to provide better feedback

[tfnribeiro]

I have noticed that some users have been reporting the error of the Extension timing out when opening it on a website. Most often it occurs when the website cannot be parsed by our backend, and currently I believe we just return a generic error / or maybe we don't even set an error.

This can lead to some users trying to open it in a website multiple times, despite not being possible to open using the extension.

There is also a consideration that if we update the extension to also allow just some fragments of text, if then we should guide the users to try that rather than the full parse.

[tfnribeiro]

After a discussion with @mircealungu, we need to also revise the way we are extracting articles. It seems some errors are caused by Newspaper failing to download & parse the article, but readability might still be able to get the data.

To work with this, we can have an Article object that can be populated by either newspaper or readability as currently we are always overriding the newspaper object with the information from readability.