LU-10938 ptlrpc: Add WBC connect flag

LU-10938 ptlrpc: Add WBC connect flag

It denotes ability of the node to understand additional
types of intent requests, exclusive metadata locks issued
to clients and server operations performed under such
locks while still held by clients.

Test-Parameters: trivial
Change-Id: I72c1ddfdf94edea3b357d82da6c410bc2d79a75c
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: https://review.whamcloud.com/32241
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>