JWT Sign and Verify updates

[nitro-neal]

A few thoughts and updates need to be made to our JWT signing logic:

Sign
// TODO: ensure that publicKeyJwk is not null
// TODO: figure out how to make more reliable since algorithm is technically not a required property of a JWK
verificationMethodId and jwt.header.keyID could be different: for example we may have a key id as a JWK thumbprint but a verification method ID as did:example:abcd#key-1

Verify
Could make a presentation definition where I'm specifically requesting expired credentials. this check would fail, since JWT validation fails if the exp property is in the past

More reference here - #184

[nitro-neal]

The only open question now is this:

// TODO: figure out how to make more reliable since algorithm is technically not a required property of a JWK

@jiyoontbd is this going to be irrelevant soon? Is jwt signing / verifying changing?

[jiyoonie9]

@nitro-neal yea, i think so. #262 introduces our own jws + jwt types, and also removes jwtutil altogether, where that todo was recorded.

closing as duplicate of #234 - let me know if you disagree and we can reopen!