Log Message:
ktextwidgets: update to 5.70.0

5.67
  Drop KWindowSystem dependency
5.70
  [NestedListHelper] Fix indentation of selection, add tests
  [NestedListHelper] Improve indentation code
  [KRichTextEdit] Make sure headings don't mess with undo stack
  [KRichTextEdit] Fix scroll jumping around when horizontal rule is added
  [KRichTextWidget] Remove ancient workaround and fix regression
  [KRichTextWidget] Add support for headings
  [KRichTextEdit] Always treat key press as single modification in undo stack
  [findreplace] Handle searching for WholeWordsOnly in Regex mode