support docker-compose `network`

[etolbakov]

At the moment network is ignored, it will be good to add network support. At the moment there are 2 options

• have a single colour for all services in one network and paste the agenda.
• wrap all services in one network in a big rectangle with the text that shows network name

links: [1]. https://docs.docker.com/compose/networking/

[etolbakov]

Initial support for network is implemented in https://github.com/etolbakov/excalidocker-rs/pull/36