core: Support Unix domain socket HTTP server listener

[LINKIWI]

This PR implements support for listening on a Unix domain socket for Burrow's main HTTP server. Users can specify an address of the form unix:/path/to/socket to enable the Unix socket listener, instead of the traditional TCP-based listener.

Test Plan

Example config:

[logging]
level="info"
use-localtime=false

[zookeeper]
servers=["localhost:2181"]
timeout=6
root-path="/burrow"

[client-profile.local]
client-id="burrow"
kafka-version="1.0.0"

[cluster.local]
class-name="kafka"
servers=["localhost:9092"]
client-profile="local"
topic-refresh=120
offset-refresh=10

[consumer.local]
class-name="kafka"
cluster="local"
servers=["localhost:9092"]
client-profile="local"
group-denylist="^(console-consumer-|python-kafka-consumer-|quick-).*$"
group-allowlist=""

[httpserver.default]
address="unix:/tmp/burrow.sock"

Usage:

$ ./bin/burrow --config-dir /tmp/burrow
Reading configuration from /tmp/burrow
{"level":"info","ts":1706928222.3937771,"msg":"Started Burrow"}

Verification:

$ curl --unix-socket /tmp/burrow.sock http://localhost/v3/kafka/local/topic
{"error":false,"message":"topic list returned","topics":[...],"request":{"url":"/v3/kafka/local/topic","host":"..."}}