Emscripten/WASI builds

[m-aciek]

Hi, would you consider adding WASI/Emscripten builds of Python?

• Emscripten compilation guide: https://devguide.python.org/contrib/workflows/compile/#emscripten
• WASI: https://devguide.python.org/contrib/workflows/compile/#wasi

WASI is 2nd tier and Emscripten is 3rd tier supported platform.