Consider renaming "Jackson3"-classes to "Jackson"

[snicoll]

Jackson2JsonRedisSerializer has been deprecated in favor of Jackson3JsonRedisSerializer. I wonder if a new major wouldn't be an opportunity to reclaim the Jackson name (i.e. JacksonJsonRedisSerializer). There might be other classes with a similar pattern.

[christophstrobl]

We've got some mix of Jackson, Jackson2 and Jackson3 naming right now. JacksonObjectReader and JacksonObjectWriter should have been Jackson2... named when we introduced them.

So we could renameJacksonObjectReader -> Jackson2ObjectReader, JacksonObjectWriter -> Jackson2ObjectReader and then move all Jackson3*named types to just Jackson.