Export both style:ruby-position and loext:ruby-position.
The later one only allows "above" and "below", obeying
ODF standard while the former one allows "inter-character",
which is added lately. Also use ODFVER_012_EXT_COMPAT
so that loext:ruby-position isn't exported only in
extended mode.

Change-Id: I7b9208f289f8253a835b2f7751549206361274e0
Reviewed-on: https://gerrit.libreoffice.org/51007Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mark Hung <marklh9@gmail.com>