Add support for Visio .vsdx files

[dwelden]

Visio should also be supported.

[fuadmefleh]

I couldn't find support for Visio via this library or others out there. I created a simple script that handles this for me now. I paired it with an LLM to analyze the images to provide even more context. This script doesn't include the LLM stuff to keep it lean.

https://github.com/fuadmefleh/visio_to_markdown