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]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-3.7@83386f6). Learn more about missing BASE report.

Additional details and impacted files

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

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