Remove accidental block layout within `tag-list`

[jkomoros]

<tag-list> has had an accidental div block layout element inside of it for a long time, which makes it impossible to use tag-list in an inline context.

This feels like the wrong default, but a lot of existing use of tag-list accidentally relies on this old behavior.

Noted while working on #670.

• [ ] Add a .block, and use in all legacy cases
• [ ] Remove tag-list.block behavior in all cases
• [ ] Remove the block property and classes