disk/cryptodisk: Add support for LUKS2 in (proc)/luks_script

disk/cryptodisk: Add support for LUKS2 in (proc)/luks_script

The sector size in bytes is added to each line and it is allowed to be
6 decimal digits long, which covers the most common cases of 512 and 4096
byte sectors with space for two additional digits as future-proofing. The
size allocation is updated to reflect this additional field. Also make
clearer the size allocation calculation.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>