ENH: add a camonitor -> kafka bridge

[tacaswell]

This is a mass-up of caproto-monitor and the guts of KafkaPublisher.

To read the values back out:

from functools import partial
from confluent_kafka import Consumer
import msgpack
import msgpack_numpy as mpn


consumer_config = {
    "bootstrap.servers": "127.0.0.1:9092",
    "group.id": "kafka-unit-test-group-id",
    "auto.offset.reset": "latest",
}


deserializer = partial(msgpack.loads, object_hook=mpn.decode)

consumer = Consumer(consumer_config)
consumer.subscribe(["demo"])

while True:
    msg = consumer.poll(1)

    if msg is None:
        # no message was delivered
        # do some work before polling again
        time.sleep(0.1)
    else:
        payload = deserializer(msg.value())
        print(payload)

Not really sure where to send this (bluesky-pods? caproto?), settled on here but happy to move.

[codecov-commenter]

Codecov Report

Merging #103 into master will increase coverage by 0.56%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #103      +/-   ##
==========================================
+ Coverage   56.61%   57.17%   +0.56%     
==========================================
  Files          13       13              
  Lines         892      892              
==========================================
+ Hits          505      510       +5     
+ Misses        387      382       -5     

Impacted Files	Coverage Δ
nslsii/_version.py	44.80% <0.00%> (+1.79%)	⬆️

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