Make LanguageModel::use_any_tool return a stream of chunks (#16262)

This PR is a refactor to pave the way for allowing the user to view and
edit workflow step resolutions. I've made tool calls work more like
normal streaming completions for all providers. The `use_any_tool`
method returns a stream of strings (which contain chunks of JSON). I've
also done some minor cleanup of language model providers in general,
removing the duplication around handling streaming responses.

Release Notes:

- N/A

crates/ollama/src/ollama.rs

@@ -4,7 +4,7 @@ use http_client::{AsyncBody, HttpClient, Method, Request as HttpRequest};
 use isahc::config::Configurable;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
-use serde_json::Value;
+use serde_json::{value::RawValue, Value};
 use std::{convert::TryFrom, sync::Arc, time::Duration};
 
 pub const OLLAMA_API_URL: &str = "http://localhost:11434";
@@ -92,7 +92,7 @@ impl Model {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[derive(Serialize, Deserialize, Debug)]
 #[serde(tag = "role", rename_all = "lowercase")]
 pub enum ChatMessage {
     Assistant {
@@ -107,16 +107,16 @@ pub enum ChatMessage {
     },
 }
 
-#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "lowercase")]
 pub enum OllamaToolCall {
     Function(OllamaFunctionCall),
 }
 
-#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[derive(Serialize, Deserialize, Debug)]
 pub struct OllamaFunctionCall {
     pub name: String,
-    pub arguments: Value,
+    pub arguments: Box<RawValue>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]