Add support for rerank model capability

[sezaru]

Description

Brief description of changes.

Type of Change

• Bug fix (non-breaking change fixing an issue)
• New feature (non-breaking change adding functionality)
• Breaking change (fix or feature causing existing functionality to change)
• Documentation update

Testing

• Tests pass (mix test)
• Quality checks pass (mix quality)

Checklist

• My code follows the project's style guidelines
• I have updated the documentation accordingly
• I have added tests that prove my fix/feature works # NOTE I didn't add tests since I didn't saw any tests for the other capabilities options in the code.
• All new and existing tests pass
• My commits follow conventional commit format
• I have NOT edited CHANGELOG.md (it is auto-generated by git_ops)
• I have NOT directly edited generated snapshot/history artifacts unless this PR intentionally regenerates them (priv/llm_db/snapshot.json, priv/llm_db/history/**) # NOTE I ran mix llm_db.build --install which updated the snapshot.json file

Related Issues

Closes agentjido/req_llm#620

[sezaru]

Hmm, the ci unit tests failed, but I don't think it has anything to do with my changes, and locally the units tests runs just fine

[mikehostetler]

@sezaru flaky test - I'm digging into it

[sezaru]

Oh, seems like the snapshot.json updated upstream and created a conflict, should I regenerate it?