add socials buttons for sign up view (fixes issue #1402)

[hmaddisb]

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest master. (If I was asked to make more changes, I have made sure to rebase onto master then too)
• is descriptively named and links to an issue number, i.e. Fixes #123

[welcome]

🎉 Thanks for opening this pull request! Please check out our contributing guidelines if you haven't already.

[catarak]

Thanks for working on this ✨ Unfortunately due to #1244 being merged in, which adds a SocialAuthButton component, I think it makes sense to close this PR and open a new one.