Add `typ` override to `Jwt.sign()`

[KendallWeihe]

In our KCC issuance work we have a couple of JWT's which need to have a JWS header typ of something other-than the default value of "JWT". Specifically, an access_token JWT (here) needs the value application/at+jwt and also a proof.jwt (here) needs the value openid4vci-proof+jwt.

We need a way, while generating a JWT (via the call Jwt.sign() right?) to override this value. For example, in web5-go we offer a Type() variadic parameter.

[KendallWeihe]

@nitro-neal this may be up your alley?

[nitro-neal]

yea good catch, we will need to update the sdks to accept and create these. I'll assign this to myself and knock these out in js and kt