Issue with AAAA records formatting

[Charles Decoux]

Code used to format IPv6 address for AAAA records in `base.py`[1] in following cases:
* Address contains `::`;
* One to four of the first nibbles in a group of four: `2001:db8:2::1`.
The test[2] relating to this part of the code is also incorrect: representing the IP `1762:B03::1:AF18` would result in the same `octet0` to `octet3` while the address is different.
A more canonical approach of the representation would be as follows:
```python
expect = {'octet0': '1762', 'octet1': '0000', 'octet2': '0000', 'octet3': '0000'
          'octet4': '0000', 'octet5': '0B03', 'octet6': '0001'
          'octet7': 'AF18', 'ip_version': 6,
          'ip_address': '1762--B03-1-AF18'}
```

References:
1. https://github.com/openstack/designate/blob/stable/victoria/designate/notification_handler/base.py#L119
2. https://github.com/openstack/designate/blob/stable/victoria/designate/tests/test_notification_handler/test_base.py#L38

[Michael Johnson (johnsom)]

Frankly Designate should not be using regex to parse these addresses at all.

It should use python ipaddress module and normalize the address (explode for example) and use __format__ on the IPv6Address object to manipulate it for other required representations.