Add tests for Pyodide build with Pixi and Node.js

[IvanIsCoding]

Follow up of #1447 and #1449. True diff: IvanIsCoding/rustworkx@pixi-pyodide...IvanIsCoding:rustworkx:test-pyodide

This builds on the preview two PRs by adding a Pixi task that does the following:

• Runs npm install to install Pyodide
• Finds the wheel from Pyodide's build
• Creates a Pyodide environment inside Node.js with rustworkx
• Mounts our tests folder into Pyodide's memory with Node.js's file system
• Runs a smoke test the full test suite inside Pyodide via Node.js

This will catch regressions for Pyodide. Because Pixi has a lockfile and so does Node.js, I think it will be reproducible.

Note that Pyodide installs NumPy and more because it is one of our dependencies. We also need to install networkx. Because Pyodide has a lockfile internally (https://github.com/pyodide/pyodide-lock) that ships in the Node distribution, I think it will keep installing the same numpy/networkx/matplotlib from a fixed URL so I think overall this will be reproducible.