Cannot configure IPv6 ERSPAN sessions from the CLI

[mramezani95]

After PR #3370 in sonic-swss repo, it is possible to configure an ERSPAN session in CONFIG_DB using IPv6 source and destination addresses (as long as both are IPv6). For example:

127.0.0.1:6379[4]> hgetall "MIRROR_SESSION|erspan_test6"
 1) "direction"
 2) "rx"
 3) "dscp"
 4) "8"
 5) "dst_ip"
 6) "fc00::2:2:2:2"
 7) "gre_type"
 8) "35145"
 9) "queue"
10) "0"
11) "src_ip"
12) "fc00::1:1:1:1"
13) "src_port"
14) "Ethernet4"
15) "ttl"
16) "4"
17) "type"
18) "ERSPAN"

However, the CLI currently does not allow IPv6 source or destination addresses:

sudo config mirror_session erspan add 'erspan_test6' 'fc00::1:1:1:1' 'fc00::2:2:2:2' 8 4 35145 0 Ethernet4 rx
Usage: config mirror_session erspan add [OPTIONS] <session_name> <src_ip>
                                        <dst_ip> <dscp> <ttl> [gre_type]
                                        [queue] [src_port] [direction]

Error: fc00::1:1:1:1 is not a valid IPv4 address