Add proto validation for entity IDs

[eleftherias]

Summary

Ref stacklok/minder-stories#94

Change Type

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• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

Outline how the changes were tested, including steps to reproduce and any relevant configurations.
Attach screenshots if helpful.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

Pull Request Test Coverage Report for Build 11664310246

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.004%) to 54.772%

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Files with Coverage Reduction	New Missed Lines	%
internal/eea/eea.go	2	73.73%

Totals
Change from base Build 11663794666:	-0.004%
Covered Lines:	15535
Relevant Lines:	28363

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💛 - Coveralls