Add observability platform Ansible project

Deploys the Grafana stack (Prometheus/Alertmanager/Loki/Tempo/Grafana with
Alloy as collector) and the ELK stack (Filebeat/Logstash/Elasticsearch/
Kibana) via Docker Compose on a target host. External to the application
repo, pre-built by the mentor.

ansible/roles/observability/templates/elk-grafana/config/filebeat/filebeat.yml.j2

@@ -0,0 +1,21 @@
+filebeat.inputs:
+  - type: filestream
+    id: docker-containers
+    enabled: true
+    paths:
+      - /var/lib/docker/containers/*/*.log
+    parsers:
+      - container:
+          stream: all
+          format: docker
+
+processors:
+  - add_docker_metadata:
+      host: unix:///var/run/docker.sock
+  - add_host_metadata: ~
+
+output.logstash:
+  hosts: ["logstash:5044"]
+
+logging.level: info
+