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

#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include <emscripten.h>
#include <stdbool.h>

#define FAIL_IF_STATUS_EXCEPTION(status)                                       \
  if (PyStatus_Exception(status)) {                                            \
    goto finally;                                                              \
  }

// Initialize python. exit() and print message to stderr on failure.
static void
initialize_python(int argc, char** argv)
{
  bool success = false;
  PyStatus status;

  PyPreConfig preconfig;
  PyPreConfig_InitPythonConfig(&preconfig);

  status = Py_PreInitializeFromBytesArgs(&preconfig, argc, argv);
  FAIL_IF_STATUS_EXCEPTION(status);

  PyConfig config;
  PyConfig_InitPythonConfig(&config);

  status = PyConfig_SetBytesArgv(&config, argc, argv);
  FAIL_IF_STATUS_EXCEPTION(status);

  status = PyConfig_SetBytesString(&config, &config.home, "/");
  FAIL_IF_STATUS_EXCEPTION(status);
  config.write_bytecode = false;
  status = Py_InitializeFromConfig(&config);
  FAIL_IF_STATUS_EXCEPTION(status);

  success = true;
finally:
  PyConfig_Clear(&config);
  if (!success) {
    // This will exit().
    Py_ExitStatusException(status);
  }
}

PyObject*
PyInit__pyodide_core(void);

/**
 * Bootstrap steps here:
 *  1. Import _pyodide package (we depend on this in _pyodide_core)
 *  2. Initialize the different ffi components and create the _pyodide_core
 *     module
 *  3. Create a PyProxy wrapper around _pyodide package so that JavaScript can
 *     call into _pyodide._base.eval_code and
 *     _pyodide._import_hook.register_js_finder (this happens in loadPyodide in
 *     pyodide.js)
 */
int
main(int argc, char** argv)
{
  // This exits and prints a message to stderr on failure,
  // no status code to check.
  PyImport_AppendInittab("_pyodide_core", PyInit__pyodide_core);
  initialize_python(argc, argv);
  emscripten_exit_with_live_runtime();
  return 0;
}

void
pymain_run_python(int* exitcode);

EMSCRIPTEN_KEEPALIVE int
run_main()
{
  int exitcode;
  pymain_run_python(&exitcode);
  return exitcode;
}

#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include <emscripten.h>
#include <stdbool.h>

#define FAIL_IF_STATUS_EXCEPTION(status)                                       \
  if (PyStatus_Exception(status)) {                                            \
    goto finally;                                                              \
  }

// Initialize python. exit() and print message to stderr on failure.
static void
initialize_python(int argc, char** argv)
{
  bool success = false;
  PyStatus status;

  PyPreConfig preconfig;
  PyPreConfig_InitPythonConfig(&preconfig);

  status = Py_PreInitializeFromBytesArgs(&preconfig, argc, argv);
  FAIL_IF_STATUS_EXCEPTION(status);

  PyConfig config;
  PyConfig_InitPythonConfig(&config);

  status = PyConfig_SetBytesArgv(&config, argc, argv);
  FAIL_IF_STATUS_EXCEPTION(status);

  status = PyConfig_SetBytesString(&config, &config.home, "/");
  FAIL_IF_STATUS_EXCEPTION(status);

  config.write_bytecode = false;
  status = Py_InitializeFromConfig(&config);
  FAIL_IF_STATUS_EXCEPTION(status);

  success = true;
finally:
  PyConfig_Clear(&config);
  if (!success) {
    // This will exit().
    Py_ExitStatusException(status);
  }
}

PyObject*
PyInit__pyodide_core(void);

/**
 * Bootstrap steps here:
 *  1. Import _pyodide package (we depend on this in _pyodide_core)
 *  2. Initialize the different ffi components and create the _pyodide_core
 *     module
 *  3. Create a PyProxy wrapper around _pyodide package so that JavaScript can
 *     call into _pyodide._base.eval_code and
 *     _pyodide._import_hook.register_js_finder (this happens in loadPyodide in
 *     pyodide.js)
 */
int
main(int argc, char** argv)
{
  // This exits and prints a message to stderr on failure,
  // no status code to check.
  PyImport_AppendInittab("_pyodide_core", PyInit__pyodide_core);
  initialize_python(argc, argv);
  emscripten_exit_with_live_runtime();
  return 0;
}

void
pymain_run_python(int* exitcode);

EMSCRIPTEN_KEEPALIVE int
run_main()
{
  int exitcode;
  pymain_run_python(&exitcode);
  return exitcode;
}
