This converts functions, code, str, bytes, bytearray, and memoryview objects to PyCodeObject,
and ensure that the object looks like a script. That means no args, no return, and no closure.
_PyCode_GetPureScriptXIData() takes it a step further and ensures there are no globals.
We also add _PyObject_SupportedAsScript() to the internal C-API.
This reverts commit 3c73cf5 (gh-133497), which itself reverted
the original commit d270bb5 (gh-133221).
We reverted the original change due to failing android tests.
The checks in _PyCode_CheckNoInternalState() were too strict,
so we've relaxed them.
"Stateless" code is a function or code object which does not rely on external state or internal state.
It may rely on arguments and builtins, but not globals or a closure. I've left a comment in
pycore_code.h that provides more detail.
We also add _PyFunction_VerifyStateless(). The new functions will be used in several later changes
that facilitate "sharing" functions and code objects between interpreters.
