Signed-off-by: Rémy Coutable <remy@rymai.me>

This gives admins the ability to send a `skip_confirmation` flag in the
`POST /users/:id/email` API endpoint to skip the verification step and
assume the given e-mail address is verified.

Closes #50876

For directories application_settings --> labels.

Partially addresses #47424.

# Conflicts:
#	app/controllers/admin/users_controller.rb
#	app/controllers/confirmations_controller.rb
#	app/controllers/profiles/emails_controller.rb
#	app/models/user.rb
#	app/services/emails/base_service.rb
#	app/services/emails/destroy_service.rb
#	app/views/devise/mailer/confirmation_instructions.html.haml
#	lib/api/users.rb
#	spec/services/emails/destroy_service_spec.rb