To do this mount all ESP partitions and check all the binaries there to see if
they match any entries in the new dbx. If we applied the update when a hash
matched, we would unintentially 'brick' the users machine, as the grub and shim
binaries *have* to be updated first.
This functionality does reimplement the PE hashing functionality found in
sbsigntools and pesign. This was done for 4 main reasons:
* There were some memory safety issues found when fuzzing random binaries
* Executing the tools hundreds of times was a lot of overhead
* Operating from a blob of immutable mmap'd memory is much faster
* We only need a very small amount of functionality from both tools
