bgpd/zebra: show command enhancements for EVPN symmetric routing

bgpd/zebra: show command enhancements for EVPN symmetric routing

0. move all global EVPN details to 'show evpn [json]' command
1. change "VRF" to "Tenant VRF" in 'show evpn vni'
2. change 'show vrf vni' command to tabular form
   and add l3-vni related params to the output
3. show evpn rmac should show refcount only in detailed output
4. show evpn next-hop should show refcount only in detailed output
5. move VRF in 'show evpn l3vni' to the end
6. add num rmacs and num nexthops to show evpn l3vni
7. remove "info" from 'show bgp vrf <> l3vni info'
8. show evpn vni <vni> should show l2vni details or l3 vni details
9. show evpn vni should show both L2 and L3 VNIs
10. show bgp l2vpn evpn - shows all global bgp l2vpn evpn details
11. show bgp l2vpn evpn vni - will show both l2 and l3 vnis
12. show bgp l2vpn evpn vni - should show both l2 and l3 vnis
13. follow camel notation for all json keys

Signed-off-by: Mitesh Kanjariya <mitesh@cumulusnetworks.com>