Support non-k8s workspaces

Currently we only scrape telemetry data from Kubernetes-deployed workspaces. Workspaces deployed currently via Docker, AWS, etc will not be discovered and therefore not covered by dashboards or alerts.

Using Grafana Agent on the client (i.e. where the workspaces are deployed), we can scrape workspaces' telemetry from non-k8s targets (e.g. Docker) by:

- discovering all containers ([`discovery.docker`](https://grafana.com/docs/agent/latest/flow/reference/components/discovery.docker/))
- scraping their metrics ([`prometheus.scrape`](https://grafana.com/docs/agent/latest/flow/reference/components/prometheus.scrape/)), and forwarding them to the Grafana Agent deployed by the helm chart ([`prometheus.receive_http`](https://grafana.com/docs/agent/latest/flow/reference/components/prometheus.receive_http/))
- scraping their logs ([`loki.source.docker`](https://grafana.com/docs/agent/latest/flow/reference/components/loki.source.docker)), and forwarding them to the Grafana Agent deployed by the helm chart ([`loki.source.api`](https://grafana.com/docs/agent/latest/flow/reference/components/loki.source.api/))

## Tasks
- [ ] Validate technical implementation
- [ ] Document solution for Docker
- [ ] Document solution for AWS
- [ ] Document solution for GCP
- [ ] Document solution for Azure
- [ ] Document solution for OpenStack

この issue では、リポジトリのファイル、テスト、エントリーポイントが指定されていません。まず discovery.docker、prometheus.scrape、prometheus.receive_http、loki.source.docker、loki.source.api を使用して Grafana Agent のフローを検証します。完了条件は、検証済みの非 Kubernetes アプローチと、Docker、AWS、GCP、Azure、OpenStack 向けのドキュメントです。

索引モデルが issue の本文から書いたものです。