Another batch of lint fixes (#36521)

- **Enable a bunch of extra lints**
- **First batch of fixes**
- **More fixes**

Release Notes:

- N/A

crates/multi_buffer/src/multi_buffer.rs

@@ -5205,13 +5205,9 @@ impl MultiBufferSnapshot {
         if offset == diff_transforms.start().0
             && bias == Bias::Left
             && let Some(prev_item) = diff_transforms.prev_item()
+            && let DiffTransform::DeletedHunk { .. } = prev_item
         {
-            match prev_item {
-                DiffTransform::DeletedHunk { .. } => {
-                    diff_transforms.prev();
-                }
-                _ => {}
-            }
+            diff_transforms.prev();
         }
         let offset_in_transform = offset - diff_transforms.start().0;
         let mut excerpt_offset = diff_transforms.start().1;