Make title field more prominent

[jacobobryant]

Right now the title field is off to the side with the rest of the metadata. I think it'd look nicer and feel less weird if it were placed above the editor, with enlarged font and stuff.

Some editors like Substack's blend the title field into the editor. That sounds like way too much work for our situation imo. I'd rather leave the editor as a mostly drop-in component and just stick a regular text input above it.

[jacobobryant]

I'm removing the good first issue label since the new data model makes this more complicated--all UI in platypub has to be done in a generic way.