Fix micropip.install to search shared libraries inside the wheel correctly

[ryanking13]

Previously, micropip was not able to locate shared libraries in the .libs directory of the wheel.

For instance, in Pyodide 0.25.0,

await pyodide.loadPackage("Shapely")

works, while

>>> import micropip
>>> await micropip.install("https://cdn.jsdelivr.net/pyodide/v0.25.0/full/Shapely-1.8.
2-cp311-cp311-emscripten_3_1_46_wasm32.whl")
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/lib/python3.11/site-packages/micropip/_commands/install.py", line 176, in ins
tall
    await asyncio.gather(*wheel_promises)
  File "/lib/python3.11/site-packages/micropip/transaction.py", line 168, in install
    await self.load_libraries(target)
  File "/lib/python3.11/site-packages/micropip/transaction.py", line 159, in load_libr
aries
    await asyncio.gather(*map(lambda dynlib: loadDynlib(dynlib, False), dynlibs))
pyodide.ffi.JsException: Error: Didn't expect to load any more file_packager files!

does not work.

This is because micropip.install does not search the path that pyodide.loadPackage looks for.

This PR fixes it by using the same API pyodide.loadPackage is using when loading shared libraries.

• changelog

[hoodmane]

Thanks @ryanking13! Could you add a changelog entry?

[hoodmane]

Maybe we should raise here? I think silently doing nothing is likely to be confusing.

[ryanking13]

I used this method to register all the wheels included in the Pyodide distribution as test wheels, as without this, they would conflict with pytest wheel, etc that I put in for testing.

I think it will be fine as long as we know what we are doing. I added some comments about it.

[ryanking13]

Oh, I forgot to update the changelog...