Add Trusted Verifiers API to EBSI

In the EBSI-VECTOR project, in June 2024 we have held a workshop on the topic of Trusted Issuers, Verifiers, and Schemas. We are aware of EBSI's current capabilities regarding Trusted Issuers (https://hub.ebsi.eu/apis/pilot/trusted-issuers-registry), Trusted Policies (https://hub.ebsi.eu/apis/pilot/trusted-policies-registry) and Trusted Schemas (https://hub.ebsi.eu/apis/pilot/trusted-schemas-registry).

We are also aware of the model based on Policies for Verifiable Credentials Presentation and Request (https://hub.ebsi.eu/vc-framework/trust-model/policies).

Despite this, we are wondering if there should still also be a Trusted Verifier Registry on the EBSI ledger itself, which (as we understand) is currently missing. In the past, we believe that scalability issues have been mentioned as a reason why no Trusted Verifier Registry exists on EBSI today.

The motivation for having such a registry would be the potential use of EBSI for eIDAS 2.0 compliant implementation, considering this legal text:

The relying party shall provide at least: (a) the information necessary to authenticate to European Digital Identity Wallets, which as a minimum includes: (i) the Member State in which the relying party is established; and (ii) the name of the relying party and, where applicable, its registration number as stated in an official record together with identification data of that official record;

In our understanding, this legal text implies that a list of Trusted Verifiers should exist somewhere (separately and in addition to the existing registry of Trusted Issuers). EBSI would be a good infrastructure for maintaining such a list.