Decouple micronaut-elasticsearch from jackson

[yawkat]

Issue description

See also: micronaut-projects/micronaut-serialization#39

[MT-Jacobs]

Here's a snippet of conversation about this from an earlier PR: #264 (comment)

One interesting thing is that Elasticsearch's RestClientTransport class requires a JsonpMapper, an elasticsearch-java interface:

https://github.com/elastic/elasticsearch-java/blob/0aecc5a/java-client/src/main/java/co/elastic/clients/transport/rest_client/RestClientTransport.java#L100-L108

The two implementations of JsonpMapper require an ObjectMapper:

https://github.com/elastic/elasticsearch-java/blob/c475ee6/java-client/src/main/java/co/elastic/clients/json/jackson/JacksonJsonpMapper.java

and a JsonProvider:

https://github.com/elastic/elasticsearch-java/blob/c475ee6/java-client/src/main/java/co/elastic/clients/json/jsonb/JsonbJsonpMapper.java

There are a couple of directions we could go here off the top of my head:

1. Provide our own implementation of JsonpMapper, either in elasticsearch-java, or here. If we're truly going to decouple from Jackson we'd likely want to tie it to JsonMapper, though that would require a custom implementation here rather than in elasticsearch-java.
2. Provide a converter from JsonMapper to JsonProvider, then use that to construct a JsonbJsonpMapper.