Support "zip" header to compress / decompress JWS payloads (similar to JWE "zip")

[Jim Sellers]

For the SMART health card tokens, they closely implemented a JWT, but with one change is that they compressed the payload like from JWE.
https://spec.smarthealth.cards/#health-cards-are-small

If the DeflateHelper.applyDecompression is called for JWT’s, that would allow this library to be used without extensions or tweaks.

[Vladimir Dzhuvinov]

Hi Jim,

I don’t recall the rationale for not not including the “zip” header from the JWE spec in the JWS RFC. I remember thinking at the time it might be useful. Would you be interested in submitting a patch? I believe the existing “zip” code from the JWE implementation can be reused. We’ll review it and if everything is good we’ll release it.