Make pyodide worker a global

[WardBrian]

This would fix the current frustration that closing then reopening a tab with pyodide inside means it needs to re-download/re-initialize

[magland]

Perhaps this should be global anyway but... more fundamentally the analysis.py react component should not unmount when a new tab is selected. This is important for other reasons, such as maintaining the splitter states and the scroll position in the editor. This needs to be changed in TabWidget. I'm not certain, but I believe a previous version of TabWidget had the property of preserving the child components.

[WardBrian]

You can prevent the tab widget from unmounting its children by using just {children} instead of {value === index && <>{children}</>} on line 59. I believe this has some potentially unintended effects like causing plotly to load in the background even when the tab isn't selected yet

[magland]

It will take some more coding that might look hacky, but I think we should have tab widget load tabs only when they are first opened, and then remember which had been opened. Requires internal state keeping track of which tabs had been opened.

[magland]

I just thought of a reason not to have a single global pyodide worker. We want to be able to kill runs, and I think that involves terminating the worker. So I think the worker should be specific to that editor window.