Add number of Robotoff opportunities for the brand

This REST request allows to ask Robotoff the count of opportunities related to a brand:
https://robotoff.openfoodfacts.org/api/v1/questions/random?count=1&lang=en&insight_types=brand&value_tag=coles

We can either:
* Don't show the "[Hunger Game]" link if count=0
* Show the link and add the number or add "-" if there is an error in the response
