edit prediction: Request trigger (#43588)

Adds a `trigger` field to the zeta1/zeta2 prediction requests so that we
can distinguish between editor, diagnostic, and zeta-cli requests.

Release Notes:

- N/A

crates/zeta_cli/src/main.rs

@@ -454,6 +454,7 @@ async fn zeta1_context(
             &snapshot,
             clipped_cursor,
             prompt_for_events,
+            cloud_llm_client::PredictEditsRequestTrigger::Cli,
             cx,
         )
     })?

crates/zeta_cli/src/predict.rs

@@ -226,7 +226,13 @@ pub async fn perform_predict(
 
     let prediction = zeta
         .update(cx, |zeta, cx| {
-            zeta.request_prediction(&project, &cursor_buffer, cursor_anchor, cx)
+            zeta.request_prediction(
+                &project,
+                &cursor_buffer,
+                cursor_anchor,
+                cloud_llm_client::PredictEditsRequestTrigger::Cli,
+                cx,
+            )
         })?
         .await?;