Add JWT and Json schema validation to credential verification process

[Oran-Dan]

Description

Check incoming credentials if they're valid JWT's and if they comply with their corresponding Json schema.

Motivation

Adds security and improves the verification process

Resources

https://crates.io/crates/jsonschema

To-do List

• Upload OBv3 Json schema to resources folder
• Add credential format parser function to select respective Json schema
• Implement Json schema validation: OBv3 via Json schema, VC 1.1 via identity.rs
• Abstract the JWT validation code from validate_linked_verifiable_presentations
• Implement JWT validation in send_credential_request
• Block credential upon failure, throw error

[nanderstabel]

Upon receiving credentials in send_credential_request we should make use of identiy.rs's JwtCredentialValidator in conjunction with our own Verifier struct.

Note that the JwtCredentialValidator validates the actual JWT as well as for validation rules according to VC DM 1.1. So that means that for OBv3 additional validation checks need to be performed through schema validation.

We already use this method of verifying for Linked VPs and Domain Linkage, so we can just use it the same way for incoming credentials.

[nanderstabel]

We should also make sure that UniMe validates that the Credentials it receives correspond with the Credential Configurations of the Issuer's metadata.

[Oran-Dan]

We should also make sure that UniMe validates that the Credentials it receives correspond with the Credential Configurations of the Issuer's metadata.

I'll make this into a seperate Issue