A text range represents a selection or cursor position, so similar to
sections or tables, it makes sense to expose the containing paragraph as
well. This new property does exactly that.

Change-Id: If92a3b5e61f13c7c14ca52bc8593a2b286a596cc
Reviewed-on: https://gerrit.libreoffice.org/40483Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>