Page Management Support: make it possible to copy documents to channels with same locale

The DocumentCopyingPageCopyEventListener, that hooks into the page copy action from the Channel Manager, does not support copying to content root folder that has the same hippotranslation:locale as the source content root folder.

.. per this code at line 177

if (StringUtils.equals(sourceTranslationLanguage, targetTranslationLanguage)) {
  throw new IllegalStateException(
   "The same translation language of the source and the target base content. Source='"
      + sourceContentBasePath + "'. Target='" + targetContentBasePath + "'.");
}

This ticket is to start supporting that.