Calculate the amount of disk space the block & undo files currently use
Declared in <node/blockstorage.h>
[[requires_capability(0x7fd7532b0ad8), requires_capability(0x7fd74e9c7a28), requires_capability(0x7fd75a26b778), requires_capability(0x7fd74f16ebf8), requires_capability(0x7fd74a00e298), requires_capability(0x7fd753265ba8)]]
uint64_t
CalculateCurrentUsage();
The total size in bytes of the block and undo files on disk.