efi_selftest: provide a test for block io

This test checks the driver for block IO devices.
A disk image is created in memory.
A handle is created for the new block IO device.
The block I/O protocol is installed on the handle.
ConnectController is used to setup partitions and to install the simple
file protocol.
A known file is read from the file system and verified.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>