Add IPv6 egress support to eks IPv4 cluster

[wanyufe]

What type of PR is this?
feature

Which issue does this PR fix:
#1925

What does this PR do / Why do we need it:
IPv6 egress support for IPv4 EKS cluster

If an issue # is not available please add repro steps and logs from IPAMD/CNI showing the issue:

Testing done on this change:
Manual testing - unit testing has finished

bash-5.1# ip -6 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
5: v6if0@if130: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 state UP 
    inet6 fd00::34/8 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::e0ac:89ff:fe27:4bdb/64 scope link 
       valid_lft forever preferred_lft forever
bash-5.1# ip -6 r
fd00::/8 dev v6if0 proto kernel metric 256 pref medium
fe80::/64 dev v6if0 proto kernel metric 256 pref medium
default via fe80::5c51:9ff:fe55:3ab2 dev v6if0 metric 1024 pref medium
bash-5.1# ping6 2600::
PING 2600::(2600::) 56 data bytes
64 bytes from 2600::: icmp_seq=1 ttl=43 time=37.6 ms
64 bytes from 2600::: icmp_seq=2 ttl=43 time=37.6 ms
64 bytes from 2600::: icmp_seq=3 ttl=43 time=37.6 ms
^C
--- 2600:: ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 37.598/37.619/37.633/0.015 ms

Automation added to e2e:

Will this PR introduce any new dependencies?:
No

Will this break upgrades or downgrades. Has updating a running cluster been tested?:
No

Does this change require updates to the CNI daemonset config files to work?:
no

Does this PR introduce any user-facing change?:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jdn5126]

Changes look good me overall, thanks @wanyufe ! Just a few nits

[jdn5126]

Did a pass focusing on optimizations, and I am realizing we may be able to get some optimizations on the delete path. Hoping so, at least.