Description

1. Move _metric to ModelWrapperBase class to avoid duplicated declaration.
2. Unify the attribute model and model_name into model_name for all model wrappers. Note this change doesn't change the argument model_name in constructors, so it won't affect the users' model configuration.
3. Change parent classes for Gemini, OpenAI, ollama and DashScope into abstract class. (Because they don't implement the abstract __call__ function defined in ModelWrapperBase, and they cannot be used by users directly.)
4. Unify name of the parent classes for Gemini, OpenAI, ollama and DashScope into xxxBase, e.g. GeminiWrapperBase
5. Create a update_monitor function in ModelWrapperBase

Checklist

Please check the following items before code is ready to be reviewed.

• Code has passed all tests
• Docstrings have been added/updated in Google Style
• Documentation has been updated
• Code is ready for review