LU-13805 tests: add unaligned io to multiop

LU-13805 tests: add unaligned io to multiop

Add memory unaligned IO support to multiop.

This will be used by tests for unaligned DIO.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I38c049690610d34564a15e57f37c052105ab2066
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49990
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Qian Yingjin <qian@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>