Support F2FS for the data partition

This adds F2FS support
- for wiping a device
- for the install "format" command.

Note: crypto data in "footer" with a default/negative length
is not supported, unlike with "ext4".

Change-Id: I8d141a0d4d14df9fe84d3b131484e9696fcd8870
Signed-off-by: JP Abgrall <jpa@google.com>