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

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

examples/chat_async.rs

@@ -0,0 +1,33 @@
+use mistralai_client::v1::{
+    chat::{ChatMessage, ChatMessageRole, ChatParams},
+    client::Client,
+    constants::Model,
+};
+
+#[tokio::main]
+async fn main() {
+    // This example suppose you have set the `MISTRAL_API_KEY` environment variable.
+    let client = Client::new(None, None, None, None).unwrap();
+
+    let model = Model::OpenMistral7b;
+    let messages = vec![ChatMessage {
+        role: ChatMessageRole::User,
+        content: "Just guess the next word: \"Eiffel ...\"?".to_string(),
+        tool_calls: None,
+    }];
+    let options = ChatParams {
+        temperature: Some(0.0),
+        random_seed: Some(42),
+        ..Default::default()
+    };
+
+    let result = client
+        .chat_async(model, messages, Some(options))
+        .await
+        .unwrap();
+    println!(
+        "{:?}: {}",
+        result.choices[0].message.role, result.choices[0].message.content
+    );
+    // => "Assistant: Tower. The Eiffel Tower is a famous landmark in Paris, France."
+}