LU-9771 flr: lfs setstripe to create a new mirror

LU-9771 flr: lfs setstripe to create a new mirror

To create a mirrored file:

1. Create a component file
  lfs setstripe -E -1 /mnt/lustre/tf

2. Add a synced mirror - create a mirror with specified layout
  lfs setstripe --component-add [--mirror[=victim_file]]
    [setstripe options] <file>

  if victim_file exists, it will split the layout from that file and
  use it as a mirror; otherwise, it will create a new mirror with
  the stripe options in 'setstripe options'.

3. [todo] support to create a mirrored file directly by
  lfs setstripe --mirror [setstripe options] --mirror [options] <file>
  flag 'LCM_USER_FL_MIRROR' is reserved for this purpose.

Test-Parameters: testlist=sanity-flr
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I470feeb1a77554bd2c990e94d8538fd3d03d7b3b
Reviewed-on: https://review.whamcloud.com/29083
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>