Revert "language: Remove buffer fingerprinting (#9007)"

This reverts commit 6f2f61c9b1.

crates/project/src/project_tests.rs

@@ -3118,7 +3118,12 @@ async fn test_buffer_is_dirty(cx: &mut gpui::TestAppContext) {
             &[language::Event::Edited, language::Event::DirtyChanged]
         );
         events.lock().clear();
-        buffer.did_save(buffer.version(), buffer.file().unwrap().mtime(), cx);
+        buffer.did_save(
+            buffer.version(),
+            buffer.as_rope().fingerprint(),
+            buffer.file().unwrap().mtime(),
+            cx,
+        );
     });
 
     // after saving, the buffer is not dirty, and emits a saved event.