Add support neural query type

[GranT1337]

Description

Adds support for neural query type for neural text search

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[dblock]

Looks good! Do you think yo could add a doc and a working sample into https://github.com/opensearch-project/opensearch-java/tree/main/guides and https://github.com/opensearch-project/opensearch-java/tree/main/samples as part of this?

[dblock]

@GranT1337 Looks like you'll need to fix spotless and such ... I'll change this whole CI doesn't run on first time committer nonsense

[reta]

@GranT1337 LGTM as well, please add changelog entry, thank you

[GranT1337]

Looks good! Do you think yo could add a doc and a working sample into https://github.com/opensearch-project/opensearch-java/tree/main/guides and https://github.com/opensearch-project/opensearch-java/tree/main/samples as part of this?

@dblock Creating a sample is quite difficult. To make a simple example, you need to:

1. Upload the ML model into a cluster.
2. Deploy the ML model.
3. Define an ingest pipeline to create embeddings on the fly.
4. Create an index to store vector data.
5. Use the uploaded model for search.

The model is quite large for a simple example, and opensearch-java currently does not allow performing these steps through Java code, i.e., sending JSON text is required.

[dblock]

I'm good with this code. I think working samples and documentation are worth it, even if difficult or has a bunch of prerequisites, but I won't hold this PR for it.