Add support for publishing on IPv6 networks

[adriancable]

♻️ Current situation

Ciao, while it can publish AAAA records over IPv4, cannot publish any records at all over IPv6. This means that on IPv6-only networks, or people who are using routers with broken IPv4 multicast support (Arris and CenturyLink - I am talking about you!), Ciao does not work. 'No Response'!

💡 Proposed solution

I recently made a PR for HAP-NodeJS which adds Avahi/D-Bus as a new advertiser. This supports IPv6 and generally I would recommend it. But some platforms don't/can't have Avahi, e.g. macOS and Windows. So there's still a hole.

So here is a PR to bridge that gap, and add IPv6 publishing to Ciao (which otherwise is pretty complete).

⚙️ Release Notes

MDNSServer.options now adds a new advertiseIpv6 option. It defaults to false, but if you set it to true it'll publish over IPv6.

Testing

Not done much, but I have tested these things on macOS and Linux, and they at least superficially work: (adding, deleting, updating records)

• advertising IPv4 only on IPv4-only networks
• advertising IPv6 only on IPv6-only networks
• advertising IPv4 only on dual stack networks
• advertising IPv6 only on dual stack networks
• advertising IPv4 and IPv6 on dual stack networks

I made the decision to implement IPv6 support by effectively creating "wrapper interfaces" around IPv6-capable network interfaces, which then get special treatment to handle IPv6 vs. IPv4 differences. Out of all possible approaches this keeps the largest proportion of the existing Ciao code intact, which I felt was important because it is very easy with mDNS to subtly break things. (I don't promise I haven't already done that, unfortunately.)

For completeness, it is probably worth adding equivalents to Avahi's publish-aaaa-on-ipv4 and publish-a-on-ipv6 options.

[coveralls]

Pull Request Test Coverage Report for Build 1706679682

• 0 of 72 (0.0%) changed or added relevant lines in 2 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.7%) to 35.089%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/Responder.ts	0	12	0.0%
src/MDNSServer.ts	0	60	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/Responder.ts	1	0%
src/MDNSServer.ts	5	6.92%

Totals
Change from base Build 1491628923:	-0.7%
Covered Lines:	1200
Relevant Lines:	3085

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💛 - Coveralls

[california444]

HI,
are there any plans to merge this PR to support IPv6 for ciao in the near future?
Thanks!