IDLE - Remove use of deprecated sys.last_xyzs in stackviewer

[terryjreedy]

#102778 deprecated sys.last_type/value/traceback in favor of sys.last_exc, added in 3.12. We cannot access system system-set sys.last_exc in 3.10 and 3.11, but we can set it from sys.last_value or sys.exec_info()[1] and nearly never set or otherwise access the deprecated values. The except is sys.last_type, sys.last_value, sys.last_traceback = excinfo in run.print_exception, which should remain as long as the REPL does the same (add comment). Any sys.last_exc = sys.last_value statements can be deleted in June 2024. There is a draft issue for this.

The files to be patched are run (where it handles exceptions or stackviewer), pyshell (where it starts stackviewer), stackviewer, and test_stackviewer. This diff has the relevant locations.

Linked PRs

• gh-102832: IDLE - remove use of deprecated sys.last_xyzs for stackviewer #103339
• [3.12] gh-102832: IDLE - remove use of deprecated sys.last_xyzs for stackviewer (GH-103339) #105526
• [3.11] gh-102832: IDLE - remove use of deprecated sys.last_xyzs for stackviewer (GH-103339) #105527
• gh-102832: IDLE - update stackviewer open #105528
• [3.12] gh-102832: IDLE - update stackviewer open (GH-105528) #105534