Allow a new GitLab.com registrant to start a free trial immediately

Problem to solve

We added the ability to trial GitLab.com Gold, which is a big step forward. Our current implementation, however, requires a user to register for GitLab.com first and then find the /billings page to start a trial.

Instead, we should be able to offer a flow for someone who has never signed up for GitLab.com before - they'd be able to click "free trial" on an about.gitlab.com page, and register for GitLab.com. On finishing their registration, they should immediately be placed into a free Gold trial.

By solving this issue, we should be able to offer a "Free Trial" button on https://about.gitlab.com/pricing/, much like we have for self-hosted.

Proposal

1. After submitting the trial form from the unified trial page on about.gitlab.com, route the user to sign-in/register at https://gitlab.com/users/sign_in if they don't have an active session.
   • If the user signs in, redirect to the namespace picker.
   • If the user registers, apply the trial to the new user's personal namespace.

What does success look like, and how can we measure that?

(If no way to measure success, link to an issue that will implement a way to measure this)

Links / references