Cleanup old stream stuff

/cc @wheresrhys @kaelig @laurent-muchacho @commuterjoy 

- Remove anything stream related from Grumman to avoid confusion!
- Rename article-card classes to article so it doesn't clash with cards
- Bring in template copying from dobi
If it's just the cards - we can now use https://github.com/Financial-Times/next-article-card-component (part of the reason for doing this class change is so we can use an article-card without styles clashing.

If we wanted to bring in entire streams...I dunno. Dobi could have an endpoint which just the stream bit as a HTML fragment that can be AJAXed in maybe.