Make Buffer::apply_ops infallible (#18089)

This PR makes the `Buffer::apply_ops` method infallible for
`text::Buffer` and `language::Buffer`.

We discovered that `text::Buffer::apply_ops` was only fallible due to
`apply_undo`, which didn't actually need to be fallible.

Release Notes:

- N/A

crates/collab/src/db/queries/buffers.rs

@@ -689,9 +689,7 @@ impl Database {
         }
 
         let mut text_buffer = text::Buffer::new(0, text::BufferId::new(1).unwrap(), base_text);
-        text_buffer
-            .apply_ops(operations.into_iter().filter_map(operation_from_wire))
-            .unwrap();
+        text_buffer.apply_ops(operations.into_iter().filter_map(operation_from_wire));
 
         let base_text = text_buffer.text();
         let epoch = buffer.epoch + 1;