Add a recovery DTBO section to boot image

For non-A/B devices, the recovery partition should
be self-sufficient and not depend on any other
partition. Since recovery may need access to devices
added to the DT by overlays(for eg.display), we need to
make sure that the the recovery image also contains
the information from the DTBO image.

The following fields are added to the boot image
header for this purpose:
-boot header version
-header size
-recovery dtbo size
-recovery dtbo address

Bug: 74763691
Test: unpack_bootimage --boot_img $OUT/recovery.img
      diff out/extracted_dtbo $TOP/device/google/wahoo-kernel/dtbo.img

Change-Id: I1969859038b84fac1e4a71f79f2f546b9cacffc8