Pin APOB blob to ABL0 version (#2447)

Closes #2446

This PR has a few moving pieces:

- When we mux the SPI flash to the host, we look up the ABL0 version (as
  a `u32`)
- Instead of always mapping the APOB, we only map it if the ABL0 version
  that's currently booting matches the ABL0 version stored alongside the
  APOB
- When we commit the APOB, we also store the ABL0 version associated
  with the most recent boot

Together, this logic means that we should only ever boot with an APOB
that matches the host boot image's ABL0 version.

The PR introduces a new `ApobRawPersistentDataV2` which includes that
ABL0 version, and deprecates the old `ApobRawPersistentData` (implicitly
V1). It also adds a higher-level `ApobPersistentData`, so that we only
use the raw type when reading/writing to flash.

Author: mkeeter