Require logged-in users for user edit and update

About to do <https://www.railstutorial.org/book/updating_and_deleting_users#sec-requiring_the_right_user>.
Finish through 9.2.2
Do friendly forwarding

When people try to access a protected page and then need to be redirected elsewhere to log in, they want to go to that page once they finally log in — not some default page like their own. This implements that sort of functionality.
9.3.1: list all users for signed-in people
add Faker gem
Finish chapter 9