Add fwu update agent deployment for linux-pc/posix

The fwu update agent can be deployed in different
execution environments to suite platform requirements.
This commit adds a deployment where the fwu update
agent runs within a command-line app for Posix
environments where the firmware image file is accessible
via standard file io. Can be built to run in a native PC
environment to enable a disk image file to be inspected.

Signed-off-by: Julian Hall <julian.hall@arm.com>
Change-Id: I3a652c7ab201c5b7059f8dd1bb6b590e6d8c4c37
17 files changed