Merge pyodide_py into python_stdlib.zip. ### Description

Merges pyodide_py.tar into python_stdlib.zip. This reduces the number of network requests during the initialization.

The original intention of splitting pyodide_py.tar from pyodide.asm.data was to give users an option to provide custom files (#2023), which is now available by modifying python_stdlib.zip directly. So I think there is no reason to have both python_stdlib.zip and pyodide_py.tar.

### Checklists

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

#ifndef PYTHON2JS_BUFFER_H
#define PYTHON2JS_BUFFER_H

/** Utilities to convert Python buffer objects to JavaScript.
 */
// clang-format off
#define PY_SSIZE_T_CLEAN
#include "Python.h"
// clang-format on
#include "hiwire.h"

/** Convert a Python buffer object to a JavaScript object.
 *
 *  \param The Python object
 *  \return The JavaScript object -- might be an Error object in the case of an
 *     exception.
 */
JsRef
_python2js_buffer(PyObject* x);

errcode WARN_UNUSED
python2js_buffer_init();

#endif /* PYTHON2JS_BUFFER_H */

#ifndef PYTHON2JS_BUFFER_H
#define PYTHON2JS_BUFFER_H

/** Utilities to convert Python buffer objects to JavaScript.
 */
// clang-format off
#define PY_SSIZE_T_CLEAN
#include "Python.h"
// clang-format on
#include "hiwire.h"

/** Convert a Python buffer object to a JavaScript object.
 *
 *  \param The Python object
 *  \return The JavaScript object -- might be an Error object in the case of an
 *     exception.
 */
JsRef
_python2js_buffer(PyObject* x);

errcode WARN_UNUSED
python2js_buffer_init();

#endif /* PYTHON2JS_BUFFER_H */
