Improve two factor UI.

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

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

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

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

hypha/apply/users/templates/two_factor/profile/disable.html

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

hypha/static_src/src/javascript/apply/two-factor-focus.js

hypha/static_src/src/sass/apply/components/_button.scss

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

hypha/static_src/src/sass/apply/main.scss