Markdown has wrong CWD

[AlexandreSajus]

Loading images in Markdown blocks is really hard currently as it seems that Markdown blocks don't have the graph's CWD.

For example, with this tree:

Using Markdown in VSCode this way works to load an image:

But when using Markdown in Pyflow, the markdown block can't find the image:

A markdown block should have its graph's CWD.

[AlexandreSajus]

In markdownblock.py, this sets a custom CWD for markdown:

self.rendered_markdown.setHtml(
            f"{dark_theme}{markdown(t)}",
            baseUrl=QUrl.fromLocalFile(cwd + os.path.sep),
        )

But for now I have not found an easy way to access the CWD from markdownblock.py