Add support for models that are exploded query params

```ts
model ExpandParameters {
  field: string;
  value: string;
}

@route("model{?param*}")
op `model`(param: ExpandParameters): void;
```
Each field in `ExpandParameters` is the query param key/value.  So this would effectively become.
```rust
query_builder.set_pair("field", param.field);
query_builder.set_pair("value", param.value);
```