Update ThirdPartyAuthCallback React page, enable the flow

[vbudhram]

Because

• We want our users to not have to bounce back and forth React pages and Backbone pages when doing a third party auth login

This pull request

• Updates the existing ThirdPartyAuthCallback to make it functional

Issue that this pull request solves

Closes: # (issue number)

Checklist

• [x] My commit is GPG signed.
• [x] If applicable, I have modified or added tests which pass locally.
• [ ] I have added necessary documentation (if appropriate).
• [ ] I have verified that my changes render correctly in RTL (if appropriate).

Other information (Optional)

I would like to land this part to unblock https://github.com/mozilla/fxa/pull/18044. This page still needs to have support for 2FA prompt and metrics, but can do that in a follow up.

[vbudhram]

I found a non-critical bug, merging this and will address in a followup.

[vbudhram]

The test failures are related to stripe api?