Crystal structure of tetrakis[μ-3-carboxy-1-(1,2,4-triazol-4-yl)adamantane-κ <sup>2</sup> <i>N</i> <sup>1</sup> : <i>N</i> <sup>2</sup> ]tetrafluoridodi-μ <sub>2</sub> -oxido-dioxidodisilver(I)divanadium(V) tetrahydrate