Support UltraDNS's Apex Alias records

It seems that currently octodns does not support the Apex Alias records that one can configure on UltraDNS. E.g. trying to dump a zone from UltraDNS with such records causes octodns-dump to crash:

octodns-dump --config-file ./config/staging.yaml --output-dir ./ stg.XXX.com. ultradns                                                                                                                   
2020-12-10T16:27:50  [4492312000] INFO  Manager __init__: config_file=./config/staging.yaml
2020-12-10T16:27:50  [4492312000] INFO  Manager __init__:   max_workers=2
2020-12-10T16:27:50  [4492312000] INFO  Manager __init__:   include_meta=False
2020-12-10T16:27:51  [4492312000] INFO  Manager dump: zone=stg.XXX.com., sources=()
Traceback (most recent call last):
  File "/Users/ndenev/te/octodns/venv/bin/octodns-dump", line 8, in <module>
    sys.exit(main())
  File "/Users/ndenev/te/octodns/venv/lib/python3.9/site-packages/octodns/cmds/dump.py", line 34, in main
    manager.dump(args.zone, args.output_dir, args.lenient, args.split,
  File "/Users/ndenev/te/octodns/venv/lib/python3.9/site-packages/octodns/manager.py", line 469, in dump
    source.populate(zone, lenient=lenient)
  File "/Users/ndenev/te/octodns/venv/lib/python3.9/site-packages/octodns/provider/ultra.py", line 290, in populate
    _type = self.RECORDS_TO_TYPE[record['rrtype']]
KeyError: 'APEXALIAS (65282)'

[ross]

Likely 2 things there:

1. The Ultra DNS provider should ignore types it/octoDNS doesn’t understand/support
2. I suspect APEXALIAS can be mapped to octoDNS’s ALIAS type, but I’m not familiar with Ultra DNS so can’t say for sure.

/cc @phelpsw who wrote the provider

[ross]

@ross When the next release is cut, the README.md should be updated to reference ALIAS support on UltraDNS.

Feel free to PR the edit now. If I’d thought of it we would have done it in the PR that added support.