ospfd: Adding per neighbour json details to GR helper detail command

ospfd: Adding per neighbour json details to GR helper detail command

Description:
	Per neighbor GR enabled information is  missing from json
	output in "show ip ospf gr helper details json" command.

      Example config:

	frr(config-router)# graceful-restart helper enable 2.2.2.2
	frr(config-router)#
	frr(config-router)# do show ip ospf  graceful-restart helper  detail

       OSPF Router with ID (10.112.156.220)

	Graceful restart helper support disabled.
	Strict LSA check is enabled.
	Helper supported for Planned and Unplanned Restarts.
	Supported Graceful restart interval: 1800(in seconds).
	Enable Router list:
		2.2.2.2,

	frr(config-router)# do show ip ospf  graceful-restart helper  detail json
	{
	 "routerId":"10.112.156.220",
	 "helperSupport":"Disabled",
	 "strictLsaCheck":"Enabled",
	 "restartSupoort":"Planned and Unplanned Restarts",
	 "supportedGracePeriod":1800,
	}
	frr(config-router)#

Signed-off-by: Rajesh Girada <rgirada@vmware.com>