[WIP] flatten JSONModelType body properties as operation parameters

[changlong-liu]

For cadl:

alias MyModel = {
   one: int32;
   two: int32;
}

op sum(...MyModel): void;

Generate as:

@overload
def sum(self, body: JSON)

@overload
def sum(self, *, one: int, two: int)

def sum(self, body: JSON, *, one: int, two: int)

The alias parameter in OpenAI cadl https://github.com/changlong-liu/autorest.python/blob/20221216-openai-flatten/packages/cadl-python/OpenAI.Inference/models/embeddings.create.cadl#L8-L23 is generated as JSON body+ flattened properties: https://github.com/changlong-liu/autorest.python/blob/20221216-openai-flatten/packages/cadl-python/cadl-output/azure/openai/_operations/_operations.py#L107-L241

[iscai-msft]

@changlong-liu i think this looks ok, can you show me what it generates in OpenAI before I merge? Thanks!

[changlong-liu]

@changlong-liu i think this looks ok, can you show me what it generates in OpenAI before I merge? Thanks!

Thanks @iscai-msft for review, generated code for OpenAI.Inference are uploaded at https://github.com/changlong-liu/autorest.python/tree/20221216-openai-flatten/packages/cadl-python/cadl-output/azure/openai, and the part related to this PR is at https://github.com/changlong-liu/autorest.python/blob/20221216-openai-flatten/packages/cadl-python/cadl-output/azure/openai/_operations/_operations.py#L107-L241