Integrate drawpyo-export Docker image

@rlespinasse created a useful Docker image with an export drawpyo file action. This could be integrated to drawpyo to support exporting a diagram to another file.

https://github.com/rlespinasse/drawio-export

There's also a Github action that can be integrated into build scripts for generating documentation! Ain't that cool.

https://github.com/rlespinasse/drawio-export-action?tab=readme-ov-file

No file, test, or entry point is named in the issue. Start by reading the linked drawio-export image and drawio-export-action documentation, then locate the relevant drawpyo integration point. Done means drawpyo can export a diagram to another file and the GitHub Action can be used in build scripts to generate documentation.

Written by the indexing model from the issue text.