UI refinements for Two-Factor authentication setup

hypha/apply/users/templates/two_factor/_wizard_actions.html

.../apply/users/templates/two_factor/core/backup_tokens.html

...ers/templates/two_factor/core/backup_tokens_password.html

hypha/apply/users/templates/two_factor/core/setup.html

...apply/users/templates/two_factor/core/setup_complete.html

hypha/static_src/src/sass/apply/components/_admin-bar.scss

hypha/static_src/src/sass/apply/components/_two-factor.scss