fix: cursor jumping while editing and external update

[ZeroRex0126]

https://github.com/tinymce/tinymce-angular/issues/425

since tinyMCE does the updating the line " this._editor.setContent(isNullOrUndefined(value) ? '' : value);" is not needed and only needed for initialization.

prove it works

https://github.com/user-attachments/assets/cd78be8a-f78d-4536-9241-0384e07e14f1