Overhaul router log handling

[smlx]

Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for changelog and subsystem label(s) applied

This change implements the router logs part of the logging infrastructure rebuild (#1297).

It introduces three new services:

• logs-tee listens for remote syslog UDP packets, and forwards them to 2 (or more) destinations.
  This is designed to allow the new router logging system to be deployed alongside the existing system until it has been tested in production. Then eventually the existing system can be removed.
• router-logs-collector takes remote syslog, converts it to JSON format and forwards it to a rabbitMQ exchange.
• logs-dispatcher takes logs from a rabbitMQ queue in batches and sends it to an elasticsearch index.

Here's the route that router logs now take:

haproxy -> logs-tee -> router-logs-collector -> rabbitMQ -> logs-dispatcher -> elasticsearch

The key changes from the existing router log infrastructure is:

• sends logs from all environments to a single "project index" in Elasticsearch.
  The aim of this is to improve Elasticsearch performance by reducing the number of indices.
  This relies on kubernetes namespace labelling with lagoon/project: <projectname>, which is read by fluentd during log parsing.
• uses fluentd parsing only (no more logstash)
• routes through rabbitMQ to provide a central buffer for logs and enable e.g. dispatching logs out to other (external) endpoints.

This PR doesn't include .lagoon.yml, because I'm not sure how to test that locally.

It does include integration tests for the new components. You can run them locally:

# bring up minimal testbed
make minishift/start MINISHIFT_MEMORY=6GB MINISHIFT_CPUS=4 && make up COMPOSE_FILE=docker-compose.logs.yaml
# run tests
make build:tests && make tests/logs
# clean up ES index
curl -s --user admin:admin -XDELETE http://localhost:9200/router-logs-local_development_cluster-mytestproject-$(date +%Y.%m)

Note that this PR builds on top of #1428, and includes #1526, #1489, #1566, #1569, #1542 which have been split out for easier review.

The easiest diff for changes in this PR is auto-build-system...logs-overhaul

Closing issues

Partially implements #1364
Closes #1298, #674
Relates to #1297, #1164, #1454, #1146

[smlx]

This is partially superseded by #1859. I'll close this one, maybe some bits will make it into another PR.