writerfilter: RTF import: fix handling of associated char properties

These are all dependent on the active \lrtch \rtlch \loch \hich \dbch.

There does not appear to be a SPRM Id for CJK bold / italic / fontsize.

Change-Id: I055ac29700ccd3b32b02c3f7685629254a6c3fd6
(cherry picked from commit fc49c052dbdbb5ab3b0a02a13143705f769b9662)
Reviewed-on: https://gerrit.libreoffice.org/9915
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>