gh-142095: Add py-bt-tss command to python-gdb.py

[vstinner]

• Issue: gdb py-bt is no more compatible with Python 3.13+ #142095

[vstinner]

Here is a draft PR which adds py-bt-tss command to python-gdb.py. It's similar to py-bt but has a completly different implementation, it reads _Py_tss_gilstate or _Py_tss_tstate variable.

Example on Python 3.13 built in release mode. py-bt fails to rebuild the Python traceback:

(gdb) py-bt
Traceback (most recent call first):
  (unable to read python frame information)

whereas py-bt-tss just works:

(gdb) py-bt-tss
Traceback (most recent call first):
  File "/home/vstinner/python/main/script.py", line 2, in <module>
    while True: