futility: Add --keyset option to sign command for BIOS and kernel

This patch adds --keyset option for sign command for BIOS_IMAGE,
RAW_FIRMWARE, RAW_KERNEL and KERN_PREAMBLE file types. The default value
of this option is '/usr/share/vboot/devkeys'. It allows futility to load
public and private keys, and keyblocks from under this path, when they
were not provided manually using their respective options.

Files loaded by default for BIOS_IMAGE and RAW_FIRMWARE:
- ${keysetdir}/firmware_data_key.vbprivk
- ${keysetdir}/firmware.keyblock
- ${keysetdir}/kernel_subkey.vbpubk

Files loaded by default for RAW_KERNEL:
- ${keysetdir}/kernel_data_key.vbprivk
- ${keysetdir}/kernel.keyblock

File loaded by default for KERN_PREAMBLE:
- ${keysetdir}/kernel_data_key.vbprivk

TEST=make runfutiltests

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: Ic4026d501d88e0de7d2c6f52c7494c639d08bd15
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3740601
Auto-Submit: Jakub Czapiga <czapiga@google.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Julius Werner <jwerner@chromium.org>
Tested-by: Jakub Czapiga <czapiga@google.com>
5 files changed