feat: jsonld-credentials

[karimStekelenburg]

Adds the low-level functionality that is required for the issuance and verification of JSON-LD based credentials (W3C).

The key features this PR includes are:

• The W3cCredentialService that can be used for signing and verifying JSON-LD based credentials and presentations.
• The W3cCredentialRepository that handles storage for JSON-LD based credentials.
• The Ed25519Signature2018 signature suite that adds support for signing and verifying Ed255192018 signatures.
• The BbsBlsSignature2020 signature suite that adds support for signing and verifying BbsBls2020 signatures.
• The BbsBlsSignatureProof2020 signature suite that adds support for deriving, signing and verifying proofs of BbsBls2020 signed credentials.

[karimStekelenburg]

@TimoGlastra I missed this during development, but apparently one of our external dependencies (@digitalbazaar/ed25519-verification-key-2020) requires Node version >=14. Can we bump AFJ's required version, or will this cause too much trouble for existing projects?

I'm not why this requirement is there yet. However, the dependency isn't that big, so we might be able to fix it by pulling it into AFJ and make some compatibility modifications.

[TimoGlastra]

Node 12 will reach EOL on 2022-04-30 (tomorrow) so I'm fine with dropping support for node12.

However looking at the code the usage of the verification key library is so minimal I'd like to remove it either way. The number of dependencies this PR adds is non-trivial and If possible it would be great to remove a few before merging (I think by removing the verification key and context dependencies we can drop 4 dependencies)

[TimoGlastra]

Nice work @karimStekelenburg! Left quite some comments, but most are cosmetic / cleanup.

[TimoGlastra]

I merged #684 and set the target of this branch to next. Good luck with the merge conflicts @karimStekelenburg 😄

[karimStekelenburg]

@TimoGlastra not sure what you mean 'just the type'. You mean we shouldn't update the context? Didn't understand what you meant by sending the link either.

[karimStekelenburg]

Instead of modifying the input object I'd use destructuring: (or is this an instance of VerificationMethod instead of a plain object?)

verificationMethod = {
   ...verificationMethod,
   publicKeyMultibase: undefined
   publicKeyBase58: pubKeyBase58
}

Jup, much better indeed 🚀

[TimoGlastra]

@TimoGlastra not sure what you mean 'just the type'. You mean we shouldn't update the context? Didn't understand what you meant by sending the link either.

It's type not @type

[karimStekelenburg]

Fixed latest comments in beeaf68.

[karimStekelenburg]

@TimoGlastra done fixing the issues, we should be ready to go.

[TimoGlastra]

DCO is failing

[karimStekelenburg]

Isn't that automatically fixed when squashing?

[TimoGlastra]

Well yes, but we can't merge without. The squash would only be valid if all commits that went into the squash are signed off

[karimStekelenburg]

Had to manually merge this into 0.3.0-pre due to some fun conflicts, but I think we're good!