LU-14592 lfsck: SEL files support

LU-14592 lfsck: SEL files support

lfsck works directly on the mdt, and therefore it can see SEL magic,
handle it properly in the lfsck code

check the extent range alignment by stripe size, as done in other
places, not by MIN_STRIPE_SIZE

Signed-off-by: Vitaly Fertman <c17818@cray.com>
Change-Id: Iae9b0583f837f107eb0e5eb36eeb70643b92a12b
HPE-bug-id: LUS-9686, LUS-9639
Reviewed-on: https://es-gerrit.dev.cray.com/158202
Reviewed-on: https://es-gerrit.dev.cray.com/158287
Reviewed-on: https://es-gerrit.dev.cray.com/158216
Reviewed-on: https://es-gerrit.dev.cray.com/158463
Reviewed-by: Alexander Boyko <c17825@cray.com>
Tested-by: Elena Gryaznova <c17455@cray.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-on: https://review.whamcloud.com/43234
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Elena Gryaznova <c17455@cray.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>