git: Pick which remote to fetch (#26897)

I don't want to fetch `--all` branch, we should can picker which remote
to fetch.

Release Notes:

- Added the `git::FetchFrom` action to fetch from a single remote.

---------

Co-authored-by: Cole Miller <cole@zed.dev>

crates/git_ui/src/picker_prompt.rs

@@ -28,6 +28,8 @@ pub fn prompt(
 ) -> Task<Option<usize>> {
     if options.is_empty() {
         return Task::ready(None);
+    } else if options.len() == 1 {
+        return Task::ready(Some(0));
     }
     let prompt = prompt.to_string().into();