language_models: Improve token counting for providers (#32853)

We push the usage data whenever we receive it from the provider to make
sure the counting is correct after the turn has ended.

- [x] Ollama 
- [x] Copilot 
- [x] Mistral 
- [x] OpenRouter 
- [x] LMStudio

Put all the changes into a single PR open to move these to separate PR
if that makes the review and testing easier.

Release Notes:

- N/A

crates/open_router/src/open_router.rs

@@ -127,6 +127,12 @@ pub struct Request {
     pub parallel_tool_calls: Option<bool>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub tools: Vec<ToolDefinition>,
+    pub usage: RequestUsage,
+}
+
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct RequestUsage {
+    pub include: bool,
 }
 
 #[derive(Debug, Serialize, Deserialize)]