Integrate DID Traits Schema

[jceb]

As discussed in the W3C CCG call on Jan 7, the proposal was made to the DID Traits schema definition be integrated with the DID Extensions registry.

• The DID Traits specification defines traits of DID methods.
• Traits are described in JSON. There are a number of example assessments for well-known DID methods in the spec repository: https://github.com/decentralized-identity/did-traits/blob/main/methods/
• A JSON Schema exists that is referenced by the traits definitions https://identity.foundation/did-traits/schemas/v0.8.0/traits.json

Current status of the specification:

• The specification has been approved by the working group.
• The specification has NOT YET received final approval by DIF.

Before creating a PR, I would like to align with you on how the integration shall done, e.g. an additional file in the methods folder methods/<DID>-traits.json or methods/traits/<DID>.json. Furthermore, it might be worth thinking about ways to visualize traits. See https://identity.foundation/did-traits/v0.8.0/#comparison-of-did-methods for an example.

@msporny