TextEditor: Move code from RefactoringChanges to RefactoringFile

Preparation for de-polymorphisation of RefactoringChangesData.

Change-Id: Ia2a8f8e2a3a403f809e67c907d3474e7c1a52417
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/texteditor/refactoringchanges.h

@@ -60,6 +60,7 @@ public:
     void appendReindentRange(const Range &range);
     void setOpenEditor(bool activate = false, int pos = -1);
     bool apply();
+    bool create(const QString &contents, bool reindent, bool openEditor);
 
 protected:
     // users may only get const access to RefactoringFiles created through