WIP: cryptsetup: add --integrity-recovery-mode

This is an attemt to start solving issue #504:

For recovery from disk failures, the authenticated, encrypted LUKS2 container needs the possibility to ignore corrupted checksums. This patch adds the necessary option for cryptsetup, and sets the option of the device upon opening.

However, there is still something missing, as checksum errors are still not being ignored, although the integrity device shows (with integritysetup status $device) "mode: read/write recovery"

Also, the documentation needs to be updated.