VCS: Replace QToolButtons in VCS toolbar with QActions

Change VcsBaseEditorParameterWidget to add actions/widgets to an
existing toolbar, instead of being a widget itself.

The class is renamed in a follow-up commit.

Task-number: QTCREATORBUG-14934
Change-Id: I473a439d12a096f4cbb64f06faa0598ee72000de
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -7269,6 +7269,11 @@ void TextEditorWidget::setCursorPosition(int pos)
     setTextCursor(tc);
 }
 
+QToolBar *TextEditorWidget::toolBar()
+{
+    return d->m_toolBar;
+}
+
 void BaseTextEditor::select(int toPos)
 {
     editorWidget()->setBlockSelection(false);