we want to be able to have multiple locally bound dns sockets in lokinet so
i restructured most of the dns subsystem in order to make this easier.
specifically, we have a new structure to dns subsystem:
* dns::QueryJob_Base
base type for holding a dns query and response with virtual methods
in charge of sending a reply to whoever requested.
* dns::PacketSource_Base
base type for reading and writing dns messages to and from wherever they came from
* dns::Resolver_Base
base type for filtering and handling of dns messages asynchronously.
* dns::Server
contextualized per endpoint dns object, responsible for all dns related isms.
this change hides all impelementation details of all of the dns components.
adds some more helper functions for parsing dns and dealing with OwnedBuffer.
overall dns becomes less of a pain with this new structure. probably.
* add srv records in RCs if we have any
* add mechanism to add SRV records for plainquic exposed ports
* resign and republish rc or introset on srv record changes
* add lokinet_add_bootstrap_rc function for adding an rc from memory
* prevent stack overflow on error closing connection in quic
* add in memory nodedb
* refactor how convotags are set as active
* add initial stubs for endpoint statistics
* refactor time stuff to be a bit cleaner
* update lnproxy script with more arguments
* wire up last of the quic stuff
* clean up udp packet generation code
* pass EndpointBase not quic tunnel for quic stuff
* add {n,h}uint16_t::FromString
* add nuint_t::FromString
* make AlignedBuffer::IsZero non constant time call for speed
