Introduce reveal_path in Platform

And implement it for MacPlatform, and instead of using an external process to run `open`, use the NSWorkspace selectFile instance method.

crates/gpui/src/platform.rs

@@ -65,6 +65,7 @@ pub trait Platform: Send + Sync {
     fn write_to_clipboard(&self, item: ClipboardItem);
     fn read_from_clipboard(&self) -> Option<ClipboardItem>;
     fn open_url(&self, url: &str);
+    fn reveal_path(&self, path: &Path);
 
     fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Result<()>;
     fn read_credentials(&self, url: &str) -> Result<Option<(String, Vec<u8>)>>;

crates/gpui/src/platform/mac/platform.rs

@@ -599,6 +599,19 @@ impl platform::Platform for MacPlatform {
         }
     }
 
+    fn reveal_path(&self, path: &Path) {
+        unsafe {
+            let full_path = ns_string(path.to_str().unwrap_or(""));
+            let root_full_path = ns_string("");
+            let workspace: id = msg_send![class!(NSWorkspace), sharedWorkspace];
+            msg_send![
+                workspace,
+                selectFile: full_path
+                inFileViewerRootedAtPath: root_full_path
+            ]
+        }
+    }
+
     fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Result<()> {
         let url = CFString::from(url);
         let username = CFString::from(username);

crates/gpui/src/platform/test.rs

@@ -173,6 +173,8 @@ impl super::Platform for Platform {
 
     fn open_url(&self, _: &str) {}
 
+    fn reveal_path(&self, _: &Path) {}
+
     fn write_credentials(&self, _: &str, _: &str, _: &[u8]) -> Result<()> {
         Ok(())
     }