Visualise multiple compose files

[stefanb]

Similar as docker compose allows passing multiple files on the CLI (via -f flag) https://docs.docker.com/compose/how-tos/multiple-compose-files/merge/

docker-compose-viz-mermaid should also allow visualising multiple compose files.

Currently it only supports one compose file as parameter. If multiple compose files are listed it fails withError: got unexpected extra argument.

It could also visually group services into boxes for each file they are defined in (with visible filename).

Not sure what happens if one compose file is referencing another via extends or include.