SOLR-15152: Export Tool should export regular and nested docs cleanly in .json, .jsonl, and javabin (second take)

[epugh]

https://issues.apache.org/jira/browse/SOLR-15152

Description

This replaces https://github.com/apache/solr/pull/33, which has many changes that have been already committed in seperate PRs already.

Solution

Started migrating over tests and the fixes to make them pass.

Tests

New tests

Checklist

Please review the following and check all that apply:

• [ ] I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• [ ] I have created a Jira issue and added the issue ID to my pull request title.
• [ ] I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• [ ] I have developed this patch against the main branch.
• [ ] I have run ./gradlew check.
• [ ] I have added tests for my changes.
• [ ] I have added documentation for the Reference Guide

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[github-actions[bot]]

This PR is now closed due to 60 days of inactivity after being marked as stale. Re-opening this PR is still possible, in which case it will be marked as active again.

[epugh]

Okay, we now support exporting regular in all the formats, maybe I will merge this... nested is it's own challenge...