pimd, pim6d: Using ttable for displaying "show ip/ipv6 pim neighbor" command output.

pimd, pim6d: Using ttable for displaying "show ip/ipv6 pim neighbor" command output.

Before:

frr# show ipv6 pim neighbor
Interface                Neighbor    Uptime  Holdtime  DR Pri
ens192            fe80::250:56ff:feb7:38de  00:10:47  00:01:28       1
ens224            fe80::250:56ff:feb7:4bad  00:10:47  00:01:28       1

After:

frr# sh ipv6 pim neighbor
 Interface  Neighbor                  Uptime    Holdtime  DR Pri
 ens192     fe80::250:56ff:feb7:38de  00:00:12  00:01:32  1
 ens224     fe80::250:56ff:feb7:4bad  00:00:12  00:01:32  1

Signed-off-by: Abhishek N R <abnr@vmware.com>