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

def test_uncaught_cpp_exceptions(selenium):
    assert (
        selenium.run_js(
            """
            await pyodide.loadPackage("cpp-exceptions-test");
            const Tests = pyodide._api.tests;
            const throwlib = pyodide._module.LDSO.loadedLibsByName["/usr/lib/cpp-exceptions-test-throw.so"].module;
            """
            """\
            function t(x){
                try {
                    throwlib.throw_exc(x);
                } catch(e){
                    let errString = Tests.convertCppException(e).toString();
                    errString = errString.replace(/[0-9]+/, "xxx");
                    return errString;
                }
            }
            return [t(1), t(2), t(3), t(4), t(5)];
            """
        )
        == [
            "CppException int: The exception is an object of type int at address xxx "
            "which does not inherit from std::exception",
            "CppException char: The exception is an object of type char at address xxx "
            "which does not inherit from std::exception",
            "CppException std::runtime_error: abc",
            "CppException myexception: My exception happened",
            "CppException char const*: The exception is an object of type char const* at "
            "address xxx which does not inherit from std::exception",
        ]
    )


def test_cpp_exception_catching(selenium):
    assert (
        selenium.run_js(
            """
            await pyodide.loadPackage("cpp-exceptions-test");
            const Module = pyodide._module;
            const catchlib = pyodide._module.LDSO.loadedLibsByName["/usr/lib/cpp-exceptions-test-catch.so"].module;
            """
            """\
            function t(x){
                const ptr = catchlib.catch_exc(x);
                const res = Module.UTF8ToString(ptr);
                Module._free(ptr);
                return res;
            }

            return [t(1), t(2), t(3), t(5)];
            """
        )
        == [
            "caught int 1000",
            "caught char 99",
            "caught runtime_error abc",
            "caught ????",
        ]
    )

def test_uncaught_cpp_exceptions(selenium):
    assert (
        selenium.run_js(
            """
            await pyodide.loadPackage("cpp-exceptions-test");
            const Tests = pyodide._api.tests;
            const throwlib = pyodide._module.LDSO.loadedLibsByName["/usr/lib/cpp-exceptions-test-throw.so"].module;
            """
            """\
            function t(x){
                try {
                    throwlib.throw_exc(x);
                } catch(e){
                    let errString = Tests.convertCppException(e).toString();
                    errString = errString.replace(/[0-9]+/, "xxx");
                    return errString;
                }
            }
            return [t(1), t(2), t(3), t(4), t(5)];
            """
        )
        == [
            "CppException int: The exception is an object of type int at address xxx "
            "which does not inherit from std::exception",
            "CppException char: The exception is an object of type char at address xxx "
            "which does not inherit from std::exception",
            "CppException std::runtime_error: abc",
            "CppException myexception: My exception happened",
            "CppException char const*: The exception is an object of type char const* at "
            "address xxx which does not inherit from std::exception",
        ]
    )


def test_cpp_exception_catching(selenium):
    assert (
        selenium.run_js(
            """
            await pyodide.loadPackage("cpp-exceptions-test");
            const Module = pyodide._module;
            const catchlib = pyodide._module.LDSO.loadedLibsByName["/usr/lib/cpp-exceptions-test-catch.so"].module;
            """
            """\
            function t(x){
                const ptr = catchlib.catch_exc(x);
                const res = Module.UTF8ToString(ptr);
                Module._free(ptr);
                return res;
            }

            return [t(1), t(2), t(3), t(5)];
            """
        )
        == [
            "caught int 1000",
            "caught char 99",
            "caught runtime_error abc",
            "caught ????",
        ]
    )
