Answers ACME HTTP-01 challenges (RFC 8555 §8.3): a Sovite.Listener
handler that serves GET /.well-known/acme-challenge/<token> from an
ETS table of {token, key_authorization} and answers everything else
with 404.
table = :ets.new(:challenges, [:public])
{Sovite.Listener, port: 80, handler: Sovite.TLS.ACME.HTTPChallenge, handler_opts: [table: table]}Requests larger than 8 KiB, or slower than 10 seconds, are dropped.