Retrieves the modification time of a vault item.
func (obj *CBVault) GetFileModificationTime(FileName string) (time.Time, error)
This method retrieves the modification time of the vault item (file, directory, symbolic link, or alternate stream) specified by FileName. The timestamps returned by this method are specified in UTC.
The value passed for FileName must be a vault-local absolute path.
Note: This method can only be called when Active is true.