[Workbench] Log-in on anonymous redirects to google sign-in with no warning; feels like phishing
tl;dr: Clicking on Login on topnav takes me to google login and this could potentially be very confusing if it's my very first time as anon user
After #5418 there is no way for users to discover the "Safe" login page if the hit the anonymous project/collection/pipeline page.
Right now we manually solve this by giving them a flat-out link to the "Safe" login page in project description.
But you could hit a collection
The only thing to hit is "log-in" and that takes you straight to a google sign-in page, which is super confusing and feels like a phishing attack almost, if you didn't realize Arvados relies on Google Account sign-ins. There's no way to even stumble onto the "Safe" page where it says " You can try it out by logging in with your Google account (for example, from GMail or Google+)."
- Instead of "log-in" say "log-in/sign-up".
- Redirect topnav "log-in" clicks to "Safe" page
- Revert #5418, they can always hit the back button, and the "Safe" pages should soon link to a list of public project/collections/pipelines soon anyway -- see screenshot
 (I hope people haven't forgotten about that part...)