Jwk Set Uri Nimbus Jwt Decoder builders should take SignatureAlgorithm

[jzheaux]

Until Resource Server supports decrypting JWK sets, it doesn't make sense to take algorithms that imply non-public information being sent over via the JWK Set Uri.

As such, JwkSetUriJwtDecoderBuilder and JwkSetUriReactiveJwtDecoderBuilder should only take SignatureAlgorithm. This can be widened later in the future as needed.