Allow copyblocks to be used together with small QByteArrays.

Authored by stikonas on Oct 28 2018, 5:22 PM.

Description

Allow copyblocks to be used together with small QByteArrays.

Add CopyTargetByteArray. CopySourceByteArray is not implemented yet.

This is only suitable for reading small amount of data such as GPT header
or FAT boot sector location. Not meant for copying whole partition because
data has to be transfered over DBus.

Differential Revision: https://phabricator.kde.org/D16487