Fix CEUndoManager grouping (#69)

### Description
Fixes #68

`DelegatedUndoManager` does not override 
```swift
func beginUndoGrouping()
func endUndoGrouping()
```
so calling
```swift
textView.undoManager?.beginUndoGrouping()
```
[here](https://github.com/CodeEditApp/CodeEditSourceEditor/blob/6b2c945501f0a5c15d8aa6d159fb2550c391bdd0/Sources/CodeEditSourceEditor/Controller/TextViewController%2BToggleComment.swift#L23) and [here](https://github.com/CodeEditApp/CodeEditSourceEditor/blob/6b2c945501f0a5c15d8aa6d159fb2550c391bdd0/Sources/CodeEditSourceEditor/Controller/TextViewController%2BIndentLines.swift#L25) does not undo as group as expected.


I also updated the names to match between the `CEUndoManager` and `UndoManager`.

### Related Issues

* #68

### Checklist

- [x] I read and understood the [contributing guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md) as well as the [code of conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

#### Before:

https://github.com/user-attachments/assets/f3d0de26-f359-464f-8fe1-15a7032fb3d7

#### After:

https://github.com/user-attachments/assets/5716a972-cb2b-41ee-bee9-218967909eed

Sources/CodeEditTextView/Utils/CEUndoManager.swift

@@ -40,6 +40,14 @@ public class CEUndoManager {
             parent?.redo()
         }
 
+        public override func beginUndoGrouping() {
+            parent?.beginUndoGrouping()
+        }
+
+        public override func endUndoGrouping() {
+            parent?.endUndoGrouping()
+        }
+
         public override func registerUndo(withTarget target: Any, selector: Selector, object anObject: Any?) {
             // no-op, but just in case to save resources:
             removeAllActions()
@@ -164,18 +172,18 @@ public class CEUndoManager {
     // MARK: - Grouping
 
     /// Groups all incoming mutations.
-    public func beginGrouping() {
+    public func beginUndoGrouping() {
         guard !isGrouping else {
-            assertionFailure("UndoManager already in a group. Call `endGrouping` before this can be called.")
+            assertionFailure("UndoManager already in a group. Call `beginUndoGrouping` before this can be called.")
             return
         }
         isGrouping = true
     }
 
     /// Stops grouping all incoming mutations.
-    public func endGrouping() {
+    public func endUndoGrouping() {
         guard isGrouping else {
-            assertionFailure("UndoManager not in a group. Call `beginGrouping` before this can be called.")
+            assertionFailure("UndoManager not in a group. Call `endUndoGrouping` before this can be called.")
             return
         }
         isGrouping = false