Fixes#20067
Our password autocomplete hints were “off” but that does not prevent current
browsers from trying to autocomplete them anyway, so use `current-password` and
`new-password` so they don't put a newly-generated password in a password
confirmation prompt, or the old password for a password renewal prompt.
* Fix client-side username validation at registration
It used the Account::USERNAME_RE regexp which is for *remote* users,
local user validation is stricter. Also take into account max username length.
* Add client-side form validation for password change
* Add client-side form validation to dedicated registration form
Previous changes only applied to the /about page, not the dedicated form on
/auth
* Verify link ownership with rel="me"
* Add explanation about verification to UI
* Perform link verifications
* Add click-to-copy widget for verification HTML
* Redesign edit profile page
* Redesign forms
* Improve responsive design of settings pages
* Restore landing page sign-up form
* Fix typo
* Support <link> tags, add spec
* Fix links not being verified on first discovery and passive updates
Claire