Add key at top level to indicate existing verified data

[tiagosimoes-euf]

Motivation

The API includes fields for verified data but most entries do not have any content there. As such, exposing verified data for all entries is not desirable at this point.

However, it may be useful to indicate whether a given entry has verified data without requiring the inclusion of verified data for all entries. This way, client applications can perform an additional scoped request when desirable.

Data processing and API structure changes

A new processed API field hasVerifiedData should return true when a given entry has any number of non-emtpy verified data fields, or false otherwise.

Further work

Update OpenAPI specification and API documentation.

[tiagosimoes-euf]

#24