fix(api): add validation entity type for policy creation

[anshbansal]

Otherwise we can get flooded with invalid policies that can cause these error logging

2025-10-07 20:16:05,218 [ForkJoinPool.commonPool-worker-62] ERROR c.datahub.authorization.PolicyEngine:286 - Unsupported field type PLATFORM
2025-10-07 20:18:05,002 [ForkJoinPool.commonPool-worker-20] ERROR c.datahub.authorization.PolicyEngine:286 - Unsupported field type PLATFORM
2025-10-07 20:18:05,004 [ForkJoinPool.commonPool-worker-71] ERROR c.datahub.authorization.PolicyEngine:286 - Unsupported field type PLATFORM

[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

Codecov Report

❌ Patch coverage is 92.50000% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ta/aspect/validation/PolicyFieldTypeValidator.java	88.88%	1 Missing and 2 partials ⚠️

📢 Thoughts on this report? Let us know!

[david-leifker]

We should prefer validation which works across all APIs. While this change protects GraphQL, it doesn't support OpenAPI or Restli. Implementing this logic as a standard validator allows for cross-API validation.

[alwaysmeticulous]

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_{Expected differences? Click here. Last updated for commit d6559d5. This comment will update as new commits are pushed.}

[david-leifker]

The implementation doesn't appear to support patch

[david-leifker]

Remove or implement patch support. This would involve reading the existing aspect, applying the patch and then evaluate. Use the aspectRetriever interface from opContext to fetch the current aspect..