ospfd: show ip ospf route json does not shown metric and tag

ospfd: show ip ospf route json does not shown metric and tag

Problem Statement:
==================
[FRR OSPF] show ip ospf route json does not shown metric and tag.

Root Cause Analysis:
===================
In function show_ip_ospf_route_external, type 2 cost is not added in json.
Hence it is not displayed.

Fix:
=================
1. Add type2cost in the json display
2. Tag was also missing, added that as well

Issue: #8729

Signed-off-by: Mobashshera Rasool <mrasool@vmware.com>