Revocation request flows triggered by different Entities than WI and CI

[peppelinux]

The revocation flow could be triggered by:

1. Legal Authority or law enforcement
2. Wallet Provider (if it enables this feature)
3. Authentic Source

The current version specify only the protocol interface between the Wallet Instance and the Credential Issuer. We probably should define protocol interfaces for the above entities in a future milestone.

@peppelinux and @fmarino-ipzs, do you agree?

Originally posted by @m-basili in #308 (comment)

[peppelinux]

During the meeting of the 31 July 2024 we have discussed that:

1. for public players PDND is suitable, not clear about playing with private sector Wallet Provider using PDND
2. for legal authorities we must provide out of band mechanisms, therefore these must be considered out of the scopes of the technical specification
3. [revoke-all proposal] wallet provider may use an endpoint about the revocation of all the credentials issued about a specific subject (if the holder enables/gives consent to inform the wallet provider about the digital credentials hold)