fix(cert): genesis: wrong received_count in StorageIdtyCertMeta

When iterating on a receiver's issuers, IdtyCertMeta were created for issuers when they hadn't already one, but it were initialized with the wrong received_count, and not updated after.

With this commit, it's initialized with a dummy value, then updated (or created) later with the right value.

https://forum.duniter.org/t/v2s-g1-data-migration/9814/2