Builder NestedCollection support

[lhazlewood]

Various collection properties exist on JwtParserBuilder, JwkBuilder, ClaimsMutator (audience), etc, and they are a pain to consistently represent across builders, with forced overloaded methods (set a single value, set a collection), and currently none of them have the ability to remove or clear existing entries if desired. The likelihood of one builder representing overloaded methods one way and another a different way is high and that possibility should be reduced/eliminated.

This PR enables a consistent collection property mutator design concept that works across all builders with collection properties, and eliminates the need for inconsistent and/or numerous overloaded methods for a cleaner/easier-to-read API.

For example:

• ClaimsMutator's audience(String), audience(Collection) and audienceSingle(String) are removed in favor of a single audience() sub-builder
• JwkBuilder operations(KeyOperation) and operations(Collection) are removed in favor of an operations() sub-builder
• ProtectedHeaderMutator -> critical() sub-builder for applied critical header parameter names
• JwtParserBuilder
  • critical(): sub-builder for supported critical header parameters
  • zip(): sub-builder for compression algorithm customization
  • enc() sub-builder for encryption algorithm customization
  • sig(): sub-builder for signature and mac algorithm customization
  • key(): sub-builder for key algorithm customization

These latter zip(), enc(), sig() and key() method names were chosen to parallel the Jwts.ZIP, Jwts.ENC, Jwts.SIG and Jwts.KEY registries