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
I think it's populated with JS. Should really have the symbol name or something for Core experience - but I think it's maybe worth a separate look at core experience as a whole at some point down the line.