This extends from QuickFormInterface, as well as ConfigurableInterface
(which adds getConfiguration(), setConfiguration(), and defaultConfiguration())
and PluginFormInterface (which adds buildConfigurationForm(),
validateConfigurationForm(), and submitConfigurationForm()).
We already implement buildForm(), validateForm(), and submitForm().
The only method this adds is getFormId(). So we will also refactor
how getFormId() works in \Drupal\farm_quick\Form\QuickForm to get
it from plugin instances instead of generating it itself.
Quick forms already extend from \Drupal\Component\Plugin\PluginBase,
which implements PluginIntrospectionInterface. There is no need for
QuickFormInterface to extend from it.
