Replace verificationMethod checks with JSON Schema based validation (publicJwk)

[bnonni]

Replace with JSON Schema based validation for publicJwk. More info about the publicJwk property can be found here: https://www.w3.org/TR/did-spec-registries/#publicJwk

https://github.com/TBD54566975/dwn-sdk-js/blob/fcea84929e12dd3e3ef0e8866b0e592a025786fa/src/jose/jws/general/verifier.ts#L74-L84

[flothjl]

@thehenrytsai interested in your thoughts on depth of validation in my first pass at this. Initially started with basic checks for required fields, but then decided might be valuable to validate there is no private properties and that the curve is valid for a keytype.

Thanks!

[thehenrytsai]

@flothjl, thanks for tackling this, I've merged in your PR! 🎆 🍾 🎊