Remove loadPackagesFromImports from runPythonAsync

[hoodmane]

Resolves #1496.

[rth]

One one side I understand the motivation for removing it #1496 (comment) on the other function loadPackagesAndRunPythonAsync is not really readable IMO and it does look like we are using a fair amount of times (and aside for examples are never using this new version of runPythonAsync).

Maybe addition an optional parameter to runPythonAsync would be more readable?

[hoodmane]

it does look like we are using a fair amount of times

I just converted everything to the old version to save energy on converting them. I think in many places package loading is not actually needed. I can go through and replace with:

await pyodide.loadPackage("some_pkg"); 
await pyodide.runPythonAsync(code)

or with just runPythonAsync if nothing is actually being loaded.
I think this is much less surprising. I think it's better to just have separate functions do_a() and do_b() than to have do_b(do_a_also=True).

[rth]

OK, then maybe we could remove loadPackagesAndRunPythonAsync as well? As you said calling it explicitly is just one extra line.