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 functools import update_wrapper
from textwrap import dedent
from typing import Any


def delete_attrs(cls):
    """Prevent attributes of a class or module from being documented.

    The top level documentation comment of the class or module will still be
    rendered.
    """
    for name in dir(cls):
        if not name.startswith("_"):
            try:
                delattr(cls, name)
            except Exception:
                pass


def docs_argspec(argspec: str) -> Any:
    """Decorator to override the argument spec of the function that is
    rendered in the docs.

    If the documentation finds a __wrapped__ attribute, it will use that to
    render the argspec instead of the function itself. Assign an appropriate
    fake function to __wrapped__ with the desired argspec.
    """

    def dec(func):
        d = func.__globals__
        TEMP_NAME = "_xxxffff___"
        assert TEMP_NAME not in d
        code = dedent(
            f"""\
            def {TEMP_NAME}{argspec}:
                pass
            """
        )
        # exec in func.__globals__ context so that type hints don't case NameErrors.
        exec(code, d)
        f = d.pop(TEMP_NAME)

        # # Run update_wrapper but keep f's annotations and don't set
        # # f.__wrapped__ (would cause an infinite loop!)
        annotations = f.__annotations__
        update_wrapper(f, func)
        f.__annotations__ = annotations
        del f.__wrapped__

        # Set wrapper to be our fake function
        func.__wrapped__ = f

        return func

    return dec

from functools import update_wrapper
from textwrap import dedent
from typing import Any


def delete_attrs(cls):
    """Prevent attributes of a class or module from being documented.

    The top level documentation comment of the class or module will still be
    rendered.
    """
    for name in dir(cls):
        if not name.startswith("_"):
            try:
                delattr(cls, name)
            except Exception:
                pass


def docs_argspec(argspec: str) -> Any:
    """Decorator to override the argument spec of the function that is
    rendered in the docs.

    If the documentation finds a __wrapped__ attribute, it will use that to
    render the argspec instead of the function itself. Assign an appropriate
    fake function to __wrapped__ with the desired argspec.
    """

    def dec(func):
        d = func.__globals__
        TEMP_NAME = "_xxxffff___"
        assert TEMP_NAME not in d
        code = dedent(
            f"""\
            def {TEMP_NAME}{argspec}:
                pass
            """
        )
        # exec in func.__globals__ context so that type hints don't case NameErrors.
        exec(code, d)
        f = d.pop(TEMP_NAME)

        # # Run update_wrapper but keep f's annotations and don't set
        # # f.__wrapped__ (would cause an infinite loop!)
        annotations = f.__annotations__
        update_wrapper(f, func)
        f.__annotations__ = annotations
        del f.__wrapped__

        # Set wrapper to be our fake function
        func.__wrapped__ = f

        return func

    return dec
