Revisit variant indication in graph node

[niharikasingh]

Based on the discussion here, #349 (comment) I removed the icon that indicated that a variant exists for now.

However, it would be nice to have some indication of a variant, either through a special icon or an accordion, or something else. This needs some thought about what would be useful and not overwhelming to the user. Clicking on a node with variants both opens a documentation panel and shows the variants, and we don't want the two effects to confuse the user.