bpo-42064: Pass module state to trace, progress, and authorizer callbacks (GH-27940)

- add print-or-clear traceback helper
- add helpers to clear and visit saved contexts
- modify callbacks to use the new callback_context struct

Modules/_sqlite/connection.h

@@ -82,10 +82,10 @@ typedef struct
      */
     PyObject* text_factory;
 
-    /* remember references to object used in trace_callback/progress_handler/authorizer_cb */
-    PyObject* function_pinboard_trace_callback;
-    PyObject* function_pinboard_progress_handler;
-    PyObject* function_pinboard_authorizer_cb;
+    // Remember contexts used by the trace, progress, and authoriser callbacks
+    callback_context *trace_ctx;
+    callback_context *progress_ctx;
+    callback_context *authorizer_ctx;
 
     /* Exception objects: borrowed refs. */
     PyObject* Warning;