Some model like glm-5、kimi-k2.5 support reasoning, but require
reasoning_effort parameter

This pr add support for setting reasoing_effort for openai compatible
models

Tested using the following config:

```json
{
  "language_models": {
    "openai_compatible": {
      "My LiteLLM": {
        "available_models": [
          {
            "name": "glm-5",
            "display_name": "glm-5",
            "max_tokens": 73728,
            "reasoning_effort": "low"
          },
          {
            "name": "kimi-k2.5",
            "display_name": "kimi-k2.5",
            "max_tokens": 262144,
            "reasoning_effort": "low"
          }
        ]
      }
    }
  }
}

```

Release Notes:

- Added a setting to control `reasoning_effort` in custom
OpenAI-compatible models