Calculate the amount of disk space the block & undo files currently use
Declared in <node/blockstorage.h>
[[requires_capability(0x7fb95f04d2d8), requires_capability(0x7fb969da7098), requires_capability(0x7fb96c563ae8), requires_capability(0x7fb9857a0ba8), requires_capability(0x7fb96cb964b8), requires_capability(0x7fb95a5b9a08)]]
uint64_t
CalculateCurrentUsage();
The total size in bytes of the block and undo files on disk.