Gracefully handle models searching for empty glob (#27370)

Sometimes we've seen models provide an empty string for the path search
glob. This assumes they meant "*" when that happens.

Separately, this also removes an unnecessary `clone` of a `String`.

Release Notes:

- N/A

crates/assistant_tools/src/path_search_tool.rs

@@ -71,7 +71,11 @@ impl Tool for PathSearchTool {
             Ok(input) => (input.offset.unwrap_or(0), input.glob),
             Err(err) => return Task::ready(Err(anyhow!(err))),
         };
-        let path_matcher = match PathMatcher::new(&[glob.clone()]) {
+
+        let path_matcher = match PathMatcher::new([
+            // Sometimes models try to search for "". In this case, return all paths in the project.
+            if glob.is_empty() { "*" } else { &glob },
+        ]) {
             Ok(matcher) => matcher,
             Err(err) => return Task::ready(Err(anyhow!("Invalid glob: {err}"))),
         };