This pull request completes the work on Jackson's reflection-free serialization also implementing the deserialization part. I added a complete explanation of what this generates in the javadocs. it also moves the registration of the generated serializers in its own `ObjectMapperCustomizer`.

Once this will be merged I believe that we could have some discussion on how to extend and generalize this work making this improvement available also to other parts of Quarkus that need to perform some sort of json serialization.

/cc @geoand @franz1981 @metacosm