Make JSON serde pluggable

[erkieh]

I needed to register custom Jackson modules (Java8, Kotlin) and Mixins (For some other external library Classes which were not serializable by the default Jackson implementation).

Also I might need to use the Micronaut Serde which is compatible with Jackson annotations and has the benefit of being GraalVM native compatible.

So I created this PR for your consideration.

[devhawk]

I like the idea here, but I think we need to plumb this thru DBOSConfig rather than a setter on JSONUtil. Plus, we need tests

[erkieh]

I like the idea here, but I think we need to plumb this thru DBOSConfig rather than a setter on JSONUtil. Plus, we need tests

it's obvious now that you say it :)

Would you guys like to implement this feature yourselves or I should work on this PR? It does not make difference to me. I can't give promises when I would be able to finish it.

[devhawk]

Do we want this to be pluggable or do we want to switch to a more robust library like Micronaut Serde?

[erkieh]

At minimum I would like to register modules and add mixins to the Jackson ObjectMapper. I also ended up activating DefaultTyping in my project.

I did try to use Micronaut Serde briefly but I could not get the @JsonTypeInfo annotation to work the same way as it does with the Jackson library. So maybe it does not support it the way DBOS needs it.