Seralize operation parameters as json(or other media type)

This is not something we supported in autorest but this is something available in openapi

See autorest issue where someone ask for support https://github.com/Azure/autorest/issues/4773
```json
{
"summary": "Return list of Scripts",
"parameters": [
{
"name": "ScriptQuery",
"in": "header",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/ScriptQuery"
}
}
}
}
]
}

```

From the openapi3 docs

> Other Serialization Methods
style and explode cover the most common serialization methods, but not all. For more complex scenarios (for example, a JSON-formatted object in the query string), you can use the content keyword and specify the media type that defines the serialization format. For more information, see [schema vs content](https://swagger.io/docs/specification/describing-parameters/#schema-vs-content).

Maybe could have something like that
```tsp
@encode("application/json")
@query
data: ComplexObject;
```