feat!: add function calling support to client.chat() & client.chat_async()

BREAKING CHANGE: Too many to count in this version. Check the README examples.

tests/v1_client_list_models_async_test.rs

@@ -9,12 +9,4 @@ async fn test_client_list_models_async() {
 
     expect!(response.object).to_be("list".to_string());
     expect!(response.data.len()).to_be_greater_than(0);
-
-    // let open_mistral_7b_data_item = response
-    //     .data
-    //     .iter()
-    //     .find(|item| item.id == "open-mistral-7b")
-    //     .unwrap();
-
-    // expect!(open_mistral_7b_data_item.id).to_be("open-mistral-7b".to_string());
 }