Rework legacy lltest executable into individual integration tests and fix various disabled/broken tests

[RyeMutt]

Description

Rework legacy lltest executable into individual integration tests and fix various disabled/broken tests

Removes dead llprimlinkinfo and related test

Remove dead llassetuploadqueue llhttpclient lltimestampcache lltranscode tests

Remove dead mock_http_client

Remove duplicate hex_dump.h

Fix crash in LLDataPacker test

Related Issues

• Please link to a relevant GitHub issue for additional context.
  • Bug Fix: Link to an issue that includes reproduction steps and testing guidance.
  • Feature/Enhancement: Link to an issue with a write-up, rationale, and requirements.

Issue Link:

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Checklist

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• All new and existing tests pass.
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• Documentation has been updated if needed.
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• I have reviewed the contributing guidelines.

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Additional Notes