[BUG] [OpenAI API] Made "parameters" field of a tool specification optional

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cognitiveservices/data-plane/AzureOpenAI/inference/preview/2024-07-01-preview/inference.yaml

### API Spec version

2024-07-01-preview

### Describe the bug

The `parameters` field of a tool specification is declared as [required](https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cognitiveservices/data-plane/AzureOpenAI/inference/preview/2024-07-01-preview/inference.yaml#L3799).

Whereas, the OpenAI doc tells that it's [optional](https://platform.openai.com/docs/api-reference/chat/create)

And indeed Azure OpenAI doesn't reject and handles properly requests with the missing `parameters` field like this one:

```json
{
"prompt": "What time is it?",
"tools": [
{
"type": "function",
"function": {
"name": "get_current_time",
"description": "This function provides the current time"
}
}
]
}
```

### Expected behavior

The `parameters` field of a tool spec is an optional fields.

### Actual behavior

The `parameters` field of a tool spec is a required field.

### Reproduction Steps

Send the request to Azure OpenAI `gpt-4` and observe that it doesn't reject the request and handles it properly by calling the tool with `{}` argument:

```json
HTTP POST AZURE_OPENAI_SERVICE/openai/deployments/gpt-4/chat/completions?api-version=2024-07-01-preview
{
"prompt": "What time is it?",
"tools": [
{
"type": "function",
"function": {
"name": "get_current_time",
"description": "This function provides the current time"
}
}
]
}
```

Response:

```json
{
"choices": [
{
"finish_reason": "tool_calls",
"index": 0,
"logprobs": null,
"message": {
"content": null,
"role": "assistant",
"tool_calls": [
{
"function": {
"arguments": "{}",
"name": "get_current_time"
},
"id": "call_rDBZsOqwqvkshflwQxrY9iS3",
"type": "function"
}
]
}
}
],
"created": 7777,
"id": "chatcmpl-8888",
"model": "gpt-4",
"object": "chat.completion",
"system_fingerprint": null,
"usage": {
"completion_tokens": 8,
"prompt_tokens": 45,
"total_tokens": 53
}
}
```

### Environment

Env is irrelevant. One could reproduce the steps by senting the HTTP request.