feat(llm): add auth.allow_override option for llm auth functionality

[oowl]

Summary

Add allow_override option to allow overriding the upstream model auth parameter or header from the caller's request.

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

/AG-92

[outsinre]

No test?

Seems if this vale is true, means auth info from the request is used, and ignore configured auth?

[StarlightIbuki]

I would name it "override_request_auth" as we are overriding the request. But anyway LGTM.

[StarlightIbuki]

The failing test seems relevant

[tysoekong]

I think this works fine! But 1 failing test with random 500.

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-13493-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-13493-to-master-to-upstream
git checkout -b cherry-pick-13493-to-master-to-upstream
ancref=$(git merge-base 9bc3deb30041dbc45b1fe44fe8069f21ab69caaa 1b9314d6cd28e2fca660f3db625619b9f6032e5e)
git cherry-pick -x $ancref..1b9314d6cd28e2fca660f3db625619b9f6032e5e