brillo: Add tool for creating EFI images.

Create an EFI partition image containing initial ab boot
application.  Additional configurations to support the 'make_efi_image'
command and pass it a list of efi paths/applications is also included

TEST=Manually tested output full-disk-image.img with qemu. Checked for
presence of EFI application and executed it. Passed unit tests for
make_efi_image using the test suite.

Change-Id: Icea2cf40bf7d0f48e3d66ecb9a9109e46877f75d
4 files changed