Support retrieving doc values of unsigned long field

[bugmakerrrrrr]

Description

Implement the LeafFieldData#getLeafValueFetcher method for unsigned long field to support retrieving doc values. Previously, attempting to use the docvalue_fields parameter to access doc values would result in a UOE being thrown.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• [x] Functionality includes testing.
• [x] API changes companion pull request created, if applicable.
• [x] Public documentation issue/PR created, if applicable.

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[bugmakerrrrrr]

@reta would you mind taking a look at this if you get a chance?

[github-actions[bot]]

:white_check_mark: Gradle check result for f300e31b58607e3aa34f855c782883e6fd0fd215: SUCCESS

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.00%. Comparing base (0363aa7) to head (f300e31). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #16543 +/- ## ============================================ - Coverage 72.00% 72.00% -0.01% + Complexity 65038 65030 -8 ============================================ Files 5313 5313 Lines 303454 303460 +6 Branches 43910 43910 ============================================ - Hits 218510 218507 -3 - Misses 67040 67067 +27 + Partials 17904 17886 -18 ```

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[opensearch-trigger-bot[bot]]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-16543-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 a2a01f821760f7f27eaf6d30b6a4daaadda9fec8
# Push it to GitHub
git push --set-upstream origin backport/backport-16543-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-16543-to-2.x.

[reta]

ah @bugmakerrrrrr could you please backport to 2.x manually? thank you!

[dbwiddis]

Changelog conflict. I think it just needed https://github.com/opensearch-project/OpenSearch/pull/16536 merged first. Will try toggling the backport label to see if it regenerates properly.