LU-18986 mgs: new target registration protocol

LU-18986 mgs: new target registration protocol

Patch adds new target registration request format with
enhanced NIDs list handling. The idea is to don't overload
mgs_target_info with extra flags and fields for NID list
description but keep such information in new structure.

NIDs list is arrays of string always and can be send
in varios manners: inline buffer, bulk, compressed,
appended, etc.

It helps also to resolve compatibility issues.

Patch includes:
- new wire structure mgs_target_nidlist
- new possible RPC format with mgs_target_nidlist buffer
- new connect flag OBD_CONNECT_MGS_NIDLIST to replace
  obsoleted OBD_CONNECT_REQPORTAL removed in commit
  1.6.0-159-gd2d56f38da ("make HEAD from b_post_cmd3")
- corresponding swabber and wirecheck

Test-Parameters: testlist=runtests clientversion=EXA6.3.2
Test-Parameters: testlist=runtests serverversion=EXA6.3.2
Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I441de467a530137f76712273b9a5f814fdb562c1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59205
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>