Support for structurizr workspace.json for layout information

[tlanfer]

We keep our architecture charts as a separate workspace.dsl file in a repository which we render via the mkdocs-kroki-plugin and then just reference it in different locations in our documentation as:

#  ContentRepositoryApp

```kroki-structurizr view-key=someSpecificView
@from_file:workspace.dsl

The automatic layouting is sometimes not ideal. Its easy enough to manually arange things to look good. Unfortunately it looks like there is no way to also provide the `workspace.json` file, which stores information on manually arranged view.

I considered if this a mkdocs-kroki-plugin limitation, but looking at the [kroki docs](https://docs.kroki.io/kroki/setup/usage/) it doesnt look like there is a way to provide more than one file to the render endpoints. 

It would be great if it was possible.

[tlanfer]

Looking into alternative approaches to render these charts, i learned that none of the available structurizr exporters even support exporting manual layouting, which i guess makes this issue a bit wishfull thinking.