feat!: add client.chat_stream() method

BREAKING CHANGE: You can't set the `stream` option for `client.chat*()`.

Either use `client.chat_stream()` if you want to use streams
or use `client.chat()` / `client.chat_async()` otherwise.

tests/v1_client_chat_stream_test.rs

@@ -0,0 +1,40 @@
+use futures::stream::StreamExt;
+use jrest::expect;
+use mistralai_client::v1::{
+    chat_completion::{ChatCompletionParams, ChatMessage, ChatMessageRole},
+    client::Client,
+    constants::Model,
+};
+
+#[tokio::test]
+async fn test_client_chat_stream() {
+    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(),
+    }];
+    let options = ChatCompletionParams {
+        temperature: Some(0.0),
+        random_seed: Some(42),
+        ..Default::default()
+    };
+
+    let stream_result = client.chat_stream(model, messages, Some(options)).await;
+    let mut stream = stream_result.expect("Failed to create stream.");
+    while let Some(chunk_result) = stream.next().await {
+        match chunk_result {
+            Ok(chunk) => {
+                if chunk.choices[0].delta.role == Some(ChatMessageRole::assistant)
+                    || chunk.choices[0].finish_reason == Some("stop".to_string())
+                {
+                    expect!(chunk.choices[0].delta.content.len()).to_be(0);
+                } else {
+                    expect!(chunk.choices[0].delta.content.len()).to_be_greater_than(0);
+                }
+            }
+            Err(e) => eprintln!("Error processing chunk: {:?}", e),
+        }
+    }
+}