make strings localizable in *.ui (bin/ui-translatable.sh)

Change-Id: I60b74cecc17352681fac7dfa0e41114515dbd6f5
Reviewed-on: https://gerrit.libreoffice.org/7536
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>