nvme-cli: Add routine to search for controller with specific attributes

nvme-cli: Add routine to search for controller with specific attributes

In preparation for searching controllers to match with connect args:

Create a new routine find_ctrl_with_connectargs() that will search the
controllers that exist in the system to find one that has attributes
that match the connect arguments specified.  If found, the routine
returns the controller name ("nvme?"). If not found, a NULL is returned.

Routine is defined as a global as a subsequent patch will use it
from the fabrics routines.

Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>