Support for RFC0510: Presentation-Exchange Attachment format for requesting and presenting proofs

[llorllale]

RFC

• validation of the presentation submission
• didcomm attachment builders

[llorllale]

Notes from today's call @soluchok @rolsonquadras @sudeshrshetty

• doubts about how RFC0511 works were works were mostly resolved
• revisit the "REQUIRED" constraint on challenge and domain in offer-credential [@llorllale ]
• dive deeper into use of present-proof V2 b/w adapters [@llorllale ]
• it still seems like issue-credential V2 can be used to push our credential manifest to the Holder l* ooks like we may reuse the schema from DIF's credential-manifest spec in our own manifest - potentially making ours a 100% reuse of theirs. Note: there is an open issue in DIF to rename "credential manifest" because it's not really a "manifest"
• Draw up some API sketches of how the aries-framework-go implementation will look like [@soluchok ]
• The framework's protocol middleware does not handle action events, only state msg events...