The data set is always OUString* in reality by now, so switch
the type accordingly. This allows dropping static_cast'ing
to OUString in multiple places already assuming that the
data is actually OUString*.
Change-Id: I53b06d799802530bbe86c09150ba23447d1a9d08
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/203206
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>