Improve autocomplete compatibility for sign-in form

[aduth]

🛠 Summary of changes

Updates the sign-in form to assign autocomplete=username to the email address field.

This resolves a log message that's output in Chrome when all levels of console logging are visible:

To simulate this and add regression coverage, the logging preference for the Capybara Selenium ChromeDriver has been changed to output all logs, so that it'd be caught by existing log output checking.

While we accept email addresses as the username, autocomplete=username appears to be the correct value for use in a sign-in form.

Related resources:

• As defined by the spec, the Username group includes inputs with type=email
• Chrome sign-in form best practices recommendations includes an example with type=email autocomplete=username
• Spec authors clarify that autocomplete=username is compatible with usernames taking the form of an email address is valid
• Related StackOverflow answer

📜 Testing Plan

Verify no console output:

1. Go to http://localhost:3000
2. Open Chrome DevTools console
3. If dropdown shows "Default levels", expand and ensure "Verbose" is checked (screenshot)
4. Refresh the page
5. Verify no console output related to autocomplete attribute

Verify test coverage:

1. git checkout main -- app/views/devise/sessions/new.html.erb
2. rspec spec/features/accessibility/visitor_pages_spec.rb:6
3. See output:

  1) Accessibility on pages that do not require authentication login / root path
     Failure/Error: raise BrowserConsoleLogError.new(javascript_errors) if javascript_errors.present?
     
     BrowserConsoleLogError:
       Unexpected browser console logging:
     
       http://127.0.0.1:58253/ - [DOM] Input elements should have autocomplete attributes (suggested: "username"): (More info: https://goo.gl/9p2vKq) %o