Measurement of ${cos}2{\beta}$ in ${B}^{0}{\rightarrow}{D}^{\mathbf{(}*\mathbf{) } }{h}^{0}$ with $D{\rightarrow}{K}_{S}^{0}{ { \pi } }^{+}{ { \pi } }^{ { - } }$ decays by a combined time-dependent Dalitz plot analysis of BaBar and Belle data