Don't access a css::table::BorderLine struct as if it was
a css::table::BorderLine2 struct, which it isn't. A proper implementation
would need to pass BorderLine2 structs around for which it would need
a css::table::TableBorder2 struct that holds BorderLine2 instead of
BorderLine, and adapt various places for API compatibility to support both.
For now use the default table::BorderLineStyle::SOLID to set the line style at
::editeng::SvxBorderLine