ECMA-376-1:2016 states that w:dir is functionally equivalent to LRE/RLE+PDF
pair around the enclosed runs. So this patch does just that.

Change-Id: Ibf9775338cc38a3bbc38a42a33fc64ae787b478f
Reviewed-on: https://gerrit.libreoffice.org/59643
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>