Add a new property loext:ruby-position to ODF filter
for the new attribute value "inter-character".

Change-Id: I193eb93fba0e2e7861b6c8635244cac36eb29a06
Reviewed-on: https://gerrit.libreoffice.org/48328Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mark Hung <marklh9@gmail.com>