Send notification and open a pop-up (feat. a confetti animation!) when badge gets awarded.
Also included:
* New `ActionLog.is_implicit_action` field. Some action types (e.g. `TRANSLATION_CREATED`) may trigger other actions (e.g. `TRANSLATION_REJECTED`) without direct user intervention. The latter actions now have `is_implicit_action` set to `True`. That allows us to only include explicit actions in badge counts.