Add line ending selector (#35392)

Partially addresses this issue #5294

Adds a selector between `LF` and `CRLF` for the buffer's line endings,
the checkmark denotes the currently selected line ending.

Selector
<img width="487" height="66" alt="image"
src="https://github.com/user-attachments/assets/13f2480f-4d2d-4afe-adf5-385aeb421393"
/>

Release Notes:

- Added line ending selector.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/language/src/buffer.rs

@@ -284,6 +284,14 @@ pub enum Operation {
         /// The language server ID.
         server_id: LanguageServerId,
     },
+
+    /// An update to the line ending type of this buffer.
+    UpdateLineEnding {
+        /// The line ending type.
+        line_ending: LineEnding,
+        /// The buffer's lamport timestamp.
+        lamport_timestamp: clock::Lamport,
+    },
 }
 
 /// An event that occurs in a buffer.
@@ -1240,6 +1248,21 @@ impl Buffer {
         self.syntax_map.lock().language_registry()
     }
 
+    /// Assign the line ending type to the buffer.
+    pub fn set_line_ending(&mut self, line_ending: LineEnding, cx: &mut Context<Self>) {
+        self.text.set_line_ending(line_ending);
+
+        let lamport_timestamp = self.text.lamport_clock.tick();
+        self.send_operation(
+            Operation::UpdateLineEnding {
+                line_ending,
+                lamport_timestamp,
+            },
+            true,
+            cx,
+        );
+    }
+
     /// Assign the buffer a new [`Capability`].
     pub fn set_capability(&mut self, capability: Capability, cx: &mut Context<Self>) {
         if self.capability != capability {
@@ -2557,7 +2580,7 @@ impl Buffer {
             Operation::UpdateSelections { selections, .. } => selections
                 .iter()
                 .all(|s| self.can_resolve(&s.start) && self.can_resolve(&s.end)),
-            Operation::UpdateCompletionTriggers { .. } => true,
+            Operation::UpdateCompletionTriggers { .. } | Operation::UpdateLineEnding { .. } => true,
         }
     }
 
@@ -2623,6 +2646,13 @@ impl Buffer {
                 }
                 self.text.lamport_clock.observe(lamport_timestamp);
             }
+            Operation::UpdateLineEnding {
+                line_ending,
+                lamport_timestamp,
+            } => {
+                self.text.set_line_ending(line_ending);
+                self.text.lamport_clock.observe(lamport_timestamp);
+            }
         }
     }
 
@@ -4814,6 +4844,9 @@ impl operation_queue::Operation for Operation {
             }
             | Operation::UpdateCompletionTriggers {
                 lamport_timestamp, ..
+            }
+            | Operation::UpdateLineEnding {
+                lamport_timestamp, ..
             } => *lamport_timestamp,
         }
     }