Container Build Caching

[sjmonson]

Summary

Store dnf and uv caches in a GitHub Action cache.

Details

Adds mount caches for dnf and uv to container image and stores their output into a action cache. Layer caching would probably be more efficient but requires a container repository for storing the intermediate layers.

Test Plan

Rerun the container build job and observe that build takes less time and skips download steps.

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• "I certify that all code in this PR is my own, except as noted below."

Use of AI

• Includes AI-assisted code completion
• Includes code generated by an AI application
• Includes AI-generated tests (NOTE: AI written tests should have a docstring that includes ## WRITTEN BY AI ##)

[jaredoconnell]

The change to use GUIDELLM_BUILD_EXTRAS alone is helpful. I didn't see any problems with the workflow changes.