LU-8998 lfs: user space tools for PFL

LU-8998 lfs: user space tools for PFL

* 'lfs getstripe' to support composite file:

   --component-count:
   Display component count only;

   --component-id|-I [comp_id]:
   When 'comp_id' is provided, display components matching the
   provided 'copm_id', otherwise, display component ID only;

   --component-flags [flags]:
   When the 'flags' is provided, dispaly components contains the
   provided 'flags', otherwise, display component flags only;

   --component-start [[+-]start]:
   When '[+-]start' is provided, display components which have
   'at most' or 'at least' or exactly same extent start, otherwise,
   display component extent start only;

   --component-end|-E [[+-]end]:
   When '[+-]end' is provided, display components which have
   'at most' or 'at least' or exactly sme extent end, otherwise,
   display component extent end only;

* 'lfs find' to support composite file:

   --component-count <[+-]count>:
   Find composite files according to component count;

   --component-flags <flags>:
   Find composite files according to component flags;

   --component-start <[+-]start>:
   Find composite files according to component extent start;

   --component-end|-E <[+-]end>:
   Find composite files according to component extent end;

* 'lfs setstripe' to support composite file:

   --component-del [-I <comp_id> | --component-flags <flags>] filename
   Delete specified component(s) from existing composite file;

   --component-add -E <end1> [stripe options]
                              -E <end2> [stripe options] ...:
   Add component(s) to an existing composite file;

   -E <end1> [stripe options] -E <end2> [stripe options] ...:
   Create composite file with specifed layout components;

* 'lfs migrate' to support migrate composite files:
   - composite layout-> plain layout;
   - plain layout -> composite layout;
   - composite layout -> composite layout;

Reviewed-on: https://review.whamcloud.com/24867

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: Ib0d3eeb7927cf83a173099c474df6539d1264370
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>