fib-show should have the ability to dump prefixes based on address-family used, or/and base don prefix/subnet value given in input

the help command would look like following

>fib-show --help
DESCRIPTION
vpnservice:fib-show

Displays fibs entries

SYNTAX
vpnservice:fib-show [options] [dummy]

ARGUMENTS
dummy
Argument not needed

OPTIONS
--af
filter on address family : ipv4, ipv6, l2vpn
--help
Display this help message
--sub
Filter on give IPv4/IPv6 prefix or subnet