Include prediction ID on edit prediction accepted/discarded events (#24480)

This PR updates the edit predictions to include the prediction ID
returned from the server on the resulting telemetry events indicating
whether the prediction was accepted or discarded.

The `prediction_id` on the events can then be correlated with the
`request_id` on the server-side prediction events.

Release Notes:

- N/A

crates/copilot/src/copilot_completion_provider.rs

@@ -242,6 +242,7 @@ impl EditPredictionProvider for CopilotCompletionProvider {
             } else {
                 let position = cursor_position.bias_right(buffer);
                 Some(InlineCompletion {
+                    id: None,
                     edits: vec![(position..position, completion_text.into())],
                     edit_preview: None,
                 })