Add some common params for mmdc

[ngocptblaplafla]

Example with all options supported

diagram:
  engine:
    mermaid:
      execpath: /usr/local/bin/mmdc
      theme: default
      configFile: 'some file like https://mermaid.js.org/schemas/config.schema.json'
      cssFile: your-theme-variables.json
      puppeteerConfigFile: /etc/puppeteer-conf.json

[tarleb]

Good idea, thank you! Pandoc uses lisp-case for variables, so it would be good if we could do the same here.

The test failure is due to the images differing. That's why we're not using embed-resources, we just want to make sure that an image is generated.

[tarleb]

It would also be important to have this new behavior documented somewhere.

[ngocptblaplafla]

It would also be important to have this new behavior documented somewhere.

I haven't found anything related yet. I used mmdc -h for getting it's params. Even puppeteerConfigFile's shortcut params (-p) doesn't work