feat: Breaking change: support conjunctions of disjunctions of conjunctions when requesting attributes in any of the three supported session types

Instead of requesting several attributes, one can now request several groups of attributes. Within each such group, attributes belonging to the same credential type always come from the same credential instance. This affects all three session types, as in each of them attributes can be disclosed.

Co-authored-by: Confiks <confiks@scriptbase.org>

- Sessions now start with a SessionRequest instead of the requestor's JWT
- Move protocol version negotiation to later in the protocol to decouple QR contents from SessionRequest
- Fix legacy in protocol
- Support for multiple keyshare servers in issuance sessions

Co-authored-by: Confiks <confiks@scriptbase.org>

Co-authored-by: Confiks <confiks@scriptbase.org>

Co-authored-by: Confiks <confiks@scriptbase.org>

Co-authored-by: Confiks <confiks@scriptbase.org>

Co-authored-by: Confiks <confiks@scriptbase.org>

Co-authored-by: Confiks <confiks@scriptbase.org>

- Extract raw information from session, and only derive for display
- Add protocol version and ABS timestamps in log entries. Include an update function for existing logs
- AttributeValue of AttributeResult is now a TranslatedString
- Removed polymorphic 'response' from log entry; populate either IssueCommitment or Prooflist instead
- Greatly simplified marshalling log entries by not using a separate struct
- Added tests for disclosure logging

Co-authored-by: Sietse Ringers <mail@sietseringers.net>

Attributes may now also remotely be made optional.

Previously this was decided by checking whether any of the scheme managers of any of the involved credetials and attributes that occur in the session uses a keyshare server. However, in case of disclosure and signing sessions, this could erroneously include attributes from disjunctions that have not been selected by the user.