Download standard libraries in a zipfile. ### Description

This is a re-work of #3166. After this PR, the standard libraries are not vendored with `pyodide.asm.data`. Instead, it is now downloaded separately in a zip file similar to how we download pyodide_py.tar.

~~The hard part of this PR is to bootstrap Python without Python source codes. This requires deep-freezing all modules that are required during the bootstrap.~~

~~As mentioned in #3539, `encodings` module is needed during the bootstrap stage, but it is a large module (> 1.0MB) containing a bunch of encodings in the world, so I tried to freeze a subset of the encodings module that is used in the bootstrap (thanks for the idea from Hood), so the size increase of pyodide.asm.wasm is only 70KB.~~

~~However, the problem of freezing only part of the module is that the current Python import system does not support it. Therefore, I added some hacks to make it work, which is explained in a comment in pyodide.ts.~~

### File size change after this PR:

Before

```
- pyodide.asm.data:
    Original size: 4555 KB
    Gzip compressed size (level 1): 3062 KB
    Gzip compressed size (level 6): 2911 KB
    Gzip compressed size (level 9): 2911 KB
    Brotli compressed size: 2522 KB
- pyodide.asm.js:
    Original size: 1186 KB
    Gzip compressed size (level 1): 246 KB
    Gzip compressed size (level 6): 208 KB
    Gzip compressed size (level 9): 208 KB
    Brotli compressed size: 169 KB
- pyodide.asm.wasm:
    Original size: 8715 KB
    Gzip compressed size (level 1): 3142 KB
    Gzip compressed size (level 6): 2791 KB
    Gzip compressed size (level 9): 2791 KB
    Brotli compressed size: 2096 KB
```

After

```
- pyodide.asm.data:
    Original size: 4 KB
    Gzip compressed size (level 1): 0 KB
    Gzip compressed size (level 6): 0 KB
    Gzip compressed size (level 9): 0 KB
    Brotli compressed size: 0 KB
- pyodide.asm.js:
    Original size: 1086 KB
    Gzip compressed size (level 1): 213 KB
    Gzip compressed size (level 6): 177 KB
    Gzip compressed size (level 9): 177 KB
    Brotli compressed size: 145 KB
- pyodide.asm.wasm:
    Original size: 8775 KB
    Gzip compressed size (level 1): 3162 KB
    Gzip compressed size (level 6): 2806 KB
    Gzip compressed size (level 9): 2806 KB
    Brotli compressed size: 2105 KB
- python_stdlib.zip:
    Original size: 2230 KB
    Gzip compressed size (level 1): 2196 KB
    Gzip compressed size (level 6): 2194 KB
    Gzip compressed size (level 9): 2194 KB
    Brotli compressed size: 2181 KB
```


### Remaining works:

- remove pyodide.asm.data: the only remaining parts inside pyodide.asm.data is our [webbrowser.py](https://github.com/pyodide/pyodide/blob/main/src/py/lib/webbrowser.py) stub, I think we can either remove it or move it into pyodide_py.
- maybe merge pyodide_py.tar into the standard libraries zipfile.
- add option to use pycompiled standard libraries.

### Checklists

- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests

from sysconfig import get_config_var

from setuptools import Extension, setup

if get_config_var("SIZEOF_VOID_P") != 4:
    # pyodide_build.pypabuild will run this three times, the first time it fails
    # and the exception is caught but the second and third times it must
    # succeed.
    raise Exception(
        """
This should appear in the log exactly one time. If it appears more than once,
the Pyodide build system has misconfigured sysconfigdata (and also the build
will fail).
"""
    )

setup(
    name="fpcast-test",
    version="0.1.1",
    author="Hood Chatham",
    author_email="roberthoodchatham@gmail.com",
    description="Test function pointer casts.",
    long_description_content_type="text/markdown",
    classifiers=[
        "Programming Language :: Python :: 3",
        "License :: OSI Approved :: MIT License",
        "Operating System :: OS Independent",
    ],
    # packages=["fpcast_test"],
    ext_modules=[Extension("fpcast_test", ["fpcast-test.c"])]
    # python_requires='>=3.6',
)

from sysconfig import get_config_var

from setuptools import Extension, setup

if get_config_var("SIZEOF_VOID_P") != 4:
    # pyodide_build.pypabuild will run this three times, the first time it fails
    # and the exception is caught but the second and third times it must
    # succeed.
    raise Exception(
        """
This should appear in the log exactly one time. If it appears more than once,
the Pyodide build system has misconfigured sysconfigdata (and also the build
will fail).
"""
    )

setup(
    name="fpcast-test",
    version="0.1.1",
    author="Hood Chatham",
    author_email="roberthoodchatham@gmail.com",
    description="Test function pointer casts.",
    long_description_content_type="text/markdown",
    classifiers=[
        "Programming Language :: Python :: 3",
        "License :: OSI Approved :: MIT License",
        "Operating System :: OS Independent",
    ],
    # packages=["fpcast_test"],
    ext_modules=[Extension("fpcast_test", ["fpcast-test.c"])]
    # python_requires='>=3.6',
)
