LUKS2 reencryption: Implement abort for initialized only operations
There's no command to abort already initialized reencryption (even --encrypt and --decrypt) in LUKS2 metadata. Once reencryption is initialized in metadata it must be completed (all data area overwritten) and this may take a lot of time.
Provide a way to abort initialized reencryption operation unless the data (re)encryption is already in progress (at least single block of actual data were (reen/en/de)crypted.)