LU-10825 lnet: add ip2nets syntax handling for peer

Allow peers to be added using ip2nets syntax, from
both command line and YAML block.

Command line example:
lnetctl peer add --ip2nets 10.10.10.[3-6,9]@tcp
lnetctl peer del --ip2nets 10.10.10.[3-6,9]@tcp

YAML example:
peer:
    ip2nets:
      - nid: 30.10.10.[3-8]@tcp
      - nid: 40.10.10.[9-40]@tcp

Test-Parameters: trivial
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I904be8d496ad2be277c3d21dc7f72cbc7ed02b50
Reviewed-on: https://review.whamcloud.com/31786


Reviewed-by: Sonia Sharma <sonia.sharma@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>