Add support for DNS chaos

[mefellows]

DNS issues are are not so common but the severity can be extremely high.

Add support for hosting a primary zone with the following HL requirements:

• Ability to "proxy" another zone
• Ability to "miss" records at a given rate (e.g. simulate RR DNS failure)
• Ability to "delay" or add latency a lookup at random or fixed rates (test local DNS caching)
• Ability to blacklist certain records, by not returning a DNS entry
• Ability to corrupt certain records, by returning an invalid response

NOTE: some of the features could be implemented using the TCP network symptom, however a dedicated DNS component that can target specific records and types of failures is preferred.

See the following for inspiration:

• https://github.com/miekg/dns
• https://github.com/looterz/grimd
• https://github.com/slene/dnsproxy/blob/master/dnsproxy.go