feat(plugins): ai-prompt-guard-plugin

[tysoekong]

Summary

This commit offers another plugin that extends the functionality of "AI Proxy" in #12207.

It compares the user's llm/v1/chat or llm/v1/completions request against a series of regular expressions, in two config arrays:

• Allow
• Deny

If the request matches any regex pattern in deny, the caller is 400'd.

If any allow is specified, by the request matches none of them, the caller is also 400'd.

Engineering design document is available for this feature, but it is quite simple. Comprehensive tests supplied.

This reason for its development, is that many of our users would like to block specific prompts, words, phrases, or otherwise more tightly control how an AI / LLM model is used, if being called via Kong, and this applies especially with the AI Proxy plugin that will simplify this process.

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 - docs being discussed internally, as part of AI-Proxy plugin in feat(plugin): ai-proxy plugin #12207

[flrgh]

Couple style nitpicks and a testing request remaining, but once those are addressed it's a 👍 from me.

[flrgh]

@locao do we have another gateway reviewer for this PR?

[locao]

@flrgh this is on me, reviewing it now.

[locao]

This seems pretty close to ready to merge.

@tysoekong do you think it's possible to add an integration test?

[locao]

Just one last clean up (but that's not a blocker) and I think we're good to go.

[team-gateway-bot]

Backport failed for release/3.6.x, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/3.6.x
git worktree add -d .worktree/backport-12337-to-release/3.6.x origin/release/3.6.x
cd .worktree/backport-12337-to-release/3.6.x
git switch --create backport-12337-to-release/3.6.x
git cherry-pick -x 93a18877a42855bddedfd01521e420603fd5544f

[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-12337-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12337-to-master-to-upstream
git checkout -b cherry-pick-12337-to-master-to-upstream
ancref=$(git merge-base 3ef9235a6c76c76a641933abafcd857c740befe0 f471cae50bb87142a953b5a036e53bf17d38c093)
git cherry-pick -x $ancref..f471cae50bb87142a953b5a036e53bf17d38c093