Capture Python stacks for cpp_pz2_events

Summary: Automatically capture Python function, file, and line frames for `cpp_pz2_events`. The weak-linked CPython 3.12/3.14 path uses the current attached interpreter state when the GIL is already held and conditionally calls `PyGILState_Ensure()` when the same Python-associated OS thread temporarily released it. Unrelated native threads retain the native C++ fallback without creating a Python thread state. The false-by-default `pai/cpp_zones:enable_cpp_pz_events_stacktrace_logging` knob gates all stack capture, non-Python binaries retain weak-link compatibility, and `zone_events` is unchanged.

Reviewed By: AndrewPardoe

Differential Revision: D116512939

fbshipit-source-id: c119557b651ab65aefd3c63e463c65a7935e3f47

Author: Darrien Glasser

third-party/folly/src/folly/python/Weak.h

@@ -45,6 +45,7 @@ Py_Weak(void) PyErr_Fetch(PyObject**, PyObject**, PyObject**);
 
 // Object Handling
 Py_Weak(PyObject*) PyObject_Repr(PyObject*);
+Py_Weak(PyObject*) PyObject_GetAttrString(PyObject*, const char*);
 
 // Unicode && Bytes Handling
 Py_Weak(char*) PyBytes_AsString(PyObject*);