fix(ndi): fix missing kid on JWS header

[cflee]

Problem

After refactor of the NDI implementation to use jose library in #595, kid is no longer being set on the ID token JWS header. This is breaking verification of the ID token JWS, as RPs need to select the appropriate key from the OP JWKS based on the kid value for verification.

Accessing signingKey.kid doesn't work as signingKey is from jose.importJWK(), which is a generic crypto library KeyObject that isn't aware of JWK and so doesn't have the concept of the kid. In the implementation prior to refactor the signingKey appears to be some kind of JWK-aware thing so it had the kid.

Closes #604

Solution

Bug Fixes:

• When constructing the ID token JWS, populate the kid header value from the original pre-parsing-into-KeyObject JSON object.

[LoneRifle]

lgtm