VBmeta's key should match with pubkey embedded in bootloader. The
bootloader pubkey is added to the APEX so that sign_virt_apex can
replace it with a new pubkey.
Bug: 193504286
Test: sign_apex --sign_tool sign_virt_apex ...
& install & run a VM
Change-Id: Ic8e5ec9cb45434691c8dce0ca09243e181dc59cc
Custom signing script is a command line tool to sign the virt apex
contents. It re-signs filesystem images and bootloader with a given key.
This will be executed in apex_util.py as a part of release key signing
process.
Bug: 193504286
Test: deapexer extract com.android.virt.apex extracted
sign_virt_apex -v key.pem extracted
Change-Id: Iee3730afd828b95268220c4c9a9ad7884eb3e54e