LU-10391 lnet: add string formating/parsing for IPv6 nids

LU-10391 lnet: add string formating/parsing for IPv6 nids

New entries for struct netstrfns:
  nf_addr2str_size
  nf_str2addr_size
which accept or report the size of the address in bytes.
New matching functions that can report or parse IPv4 and IPv6
addresses.

New interface - currently unused - libcfs_strnid() which takes a str
and provides a 'struct lnet_nid' with appropriate nid_size.

Test-Parameters: trivial
Test-Parameters: serverversion=2.12 serverdistro=el7.9 testlist=runtests
Test-Parameters: clientversion=2.12 testlist=runtests
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Idbfc8bb9502192e1dc6a217750e7f4431e3eca4a
Reviewed-on: https://review.whamcloud.com/43942
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>