A new document uses the default value of ::Environment for the
RES_FRAMEDIR property. On export, of course a default value does
nothing, and for MS formats a nothing means LTR, even though
in Writer the styles setting was determined by the Locale. So RTL
users were finding their new documents switch to LTR style values
when round-tripping to MS formats.

Since this is properly handled when the property is ::SET (as it normally
is when a document is imported), make sure the the default paragraph
style's RES_FRAMEDIR is ::SET, and the export should take care of it.

This works out of the box for DOCX. The export for the other
formats needs a bit of extra tweaking in addition to this
general patch. The tweaking will be done separately.

Change-Id: I5134a636ee3374bb2c1081fd0f3f6d9e79634cd3
Reviewed-on: https://gerrit.libreoffice.org/66964
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>