Add #[track_caller] to gpui foreground executor spawn methods (#24103)

Use of this location info was added in #21758 to help with diagnosing
remote_server panics on drop of tasks on a different thread.

Release Notes:

- N/A

crates/gpui/src/app/async_context.rs

@@ -172,6 +172,7 @@ impl AsyncApp {
     }
 
     /// Schedule a future to be polled in the background.
+    #[track_caller]
     pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncApp) -> Fut) -> Task<R>
     where
         Fut: Future<Output = R> + 'static,
@@ -297,6 +298,7 @@ impl AsyncWindowContext {
 
     /// Schedule a future to be executed on the main thread. This is used for collecting
     /// the results of background tasks and updating the UI.
+    #[track_caller]
     pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
     where
         Fut: Future<Output = R> + 'static,