fix: Look in known subfolders for configs for clip variants

[brandonrising]

Summary

Currently if a text encoder is in a subfolder of a climpembed, we have no way of determining its variant. This enables our probe to search deeper than the root directory.

QA Instructions

Install InvokeAI/clip-vit-large-patch14-text-encoder::bfloat16 and validate it checks the text_encoder via debugger

Merge Plan

Can be merged when approved

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[psychedelicious]

Tested with both directly instsalling the CLIP text encoder and installing a FLUX schnell dev, which installs the CLIP text encoder as a dependency.