Add nil check to apikey suppliedIn

[nginx-bot]

Proposed changes

Add nil check in apiKey auth policy's suppliedIn field.

Instead of a stack trace, the policy will now be invalid

I20241030 11:30:59.581640   1 controller.go:2430] Skipping invalid Policy default/api-key-policy: spec.apiKey.suppliedIn: Required value: suppliedIn cannot be nil

A VS that uses an invalid policy will then return 500s for each request.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• [ ] I have read the CONTRIBUTING doc
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked that all unit tests pass after adding my changes
• [ ] I have updated necessary documentation
• [ ] I have rebased my branch onto main
• [ ] I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov[bot]]

Codecov Report

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

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-3.7 #6735 +/- ## ============================================== Coverage ? 52.99% ============================================== Files ? 85 Lines ? 19764 Branches ? 0 ============================================== Hits ? 10473 Misses ? 8885 Partials ? 406 ```

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