f2fs_io: support move_range command

This patch supports a new sub-command 'move_range' in f2fs_io
to move a range of data blocks from source file to destination
file via F2FS_IOC_MOVE_RANGE ioctl.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>