Add support for resolving CAA records

[jfromaniello]

This type of record is defined by rfc6844.

IANA has assigned Resource Record Type 257 for the CAA Resource
Record Type and added the line depicted below to the registry named
"Resource Record (RR) TYPEs" and QTYPEs as defined in BCP 42
[RFC6195] and located at
http://www.iana.org/assignments/dns-parameters.

• Version: v8.6.0
• Platform: all
• Subsystem: dns

> dns.resolve('example.com', 'CAA', (err, recs) => console.log(recs))
Error: Unknown type "CAA"
    at Resolver.resolve (dns.js:316:11)
    at repl:1:5
    at ContextifyScript.Script.runInThisContext (vm.js:50:33)
    at REPLServer.defaultEval (repl.js:239:29)
    at bound (domain.js:301:14)
    at REPLServer.runBound [as eval] (domain.js:314:12)
    at REPLServer.onLine (repl.js:440:10)
    at emitOne (events.js:120:20)
    at REPLServer.emit (events.js:210:7)
    at REPLServer.Interface._onLine (readline.js:282:10)

[tniessen]

Not sure whether c-ares supports CAA, probably something for #14713.

[bnoordhuis]

Not sure whether c-ares supports CAA

It doesn't.

[bnoordhuis]

Continues in #14713.

[coolaj86]

Has this been implemented in the https module? Or is that still vulnerable?

Must CAA checks must be done in a side channel / layered in a client library?