proto: enum definitions should follow the *_UNSPECIFIED guideline #736
Description
One last thing from my side. I'm reading this, and I think it would be a good moment to rename all *_UNKNOWN enums we have to *_UNSPECIFIED, to align with the recommendations.
Also, please check if we have an enum without an UNKNOWN/UNSPECIFIED zero-value
Originally posted by @sergio-mena in #495 (comment)