Plain dm-crypt device management enhancements.

• add option "plain" in crypttab for non-LUKS devices
• add option "swap" in crypttab only for devices with random key
• add option "tmp" in crypttab even if mountpoint is not /tmp
• add explicit filesystem to option "tmp" in crypttab
• allow all POSIX filesystems on encrypted devices with random key
• use partman info instead of only cryptsetup to check if LUKS device before retrieving LUKS UUID
• use PARTUUID or /dev/disk/by-id/* if available instead of non-persistent device file for plain devices in crypttab

Closes: #995108 and possibly #697905