RFE: Add support for LUKS2 decryption with data shift (both offline and online variants)
New feature description
We should support LUKS2 decryption with data shift (aka move data back at the head of data device) from cryptsetup cli. It's a missing feature when compared with legacy reencryption code in cryptsetup-reencrypt.
Additional info
I've seen multiple reports where users are trying to force LUKS2 decryption with embedded headers passed in --header parameter on command line. We have disabled it in 2.3.6/2.4.0, but unfortunately there's another ugly hack that can bypass the limitation via luksHeaderBackup:
See dicussion in #614 (closed)