certify_bootimg: support boot images archive

This allows us to certify multiple boot images in a
zip archive.

An usage example:
  certify_bootimg --boot_img_zip boot-img.zip \
      --algorithm SHA256_RSA4096 \
      --key external/avb/test/data/testkey_rsa4096.pem \
      --extra_args "--prop foo:bar" \
      --extra_args "--prop gki:nice" \
      --output boot-certified-img.zip

Bug: 223288963
Test: atest --host certify_bootimg_test
Change-Id: I5ea8b81cfc79b7e00fd530d2ac3c8418b9a6568b
2 files changed