Rework how we allow to set (query) attributes of models

[zimmski]

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• I have searched the existing feature requests, latest roadmap and open pull requests.

Problem

OpenAI's o3-mini requires to set reasoning_effort to either low, medium (default) or high.

Solution (optional)

The current implementation allows to set the attribute over the CLI option: --model custom-openai/o3-mini-2025-01-31/reasoning_effort=high. However this is kind of a hack. Find a better way UX and code-wise.

Tasks:

• Do the hack-implementation: We use "@" because ":" is taken by model names already.
• Add at least a test for the hack: check that the full ID is used in the logs and result path directories
• Revamp how we hold model IDs e.g. in llm.Model we now have "id" and "modelID" because the first includes even attributes that are nice to see in the logs/result-directories.
• TODO