sfdisk: add --wipe-partitions=auto|never|default

sfdisk: add --wipe-partitions=auto|never|default

The option allows to remove filesystes/RAIDs from newly created
partitions before the partition table is updated (and partition
device created).

The default is "auto" in this case wipe is enabled in interactive mode
only and user's confirmation (yes/no dialog) is required. Note that
keep filesystem signature on partition is pretty valid use-case, so we
don't erase anything by default.

Signed-off-by: Karel Zak <kzak@redhat.com>