GH-121634: enable wasm32-wasip2

[brettcannon]

Keeping it as a draft until I hear from @mdboom and @ericsnowcurrently as to whether they would sponsor under PEP 11.

• Issue: Test the wasm32-wasip2 target triple #121634

[brettcannon]

And I will say, regardless of sponsorship, I will get the wasi.py changes merged in, so I might break this PR up in the end.

[vstinner]

Is this PR still relevant since #121634 was closed?

[brettcannon]

@vstinner the part that tweaks some of configure.in is, but I'm going to do that in a separate PR. I honestly thought I had closed this. 😅