fix uncaught BdbQuit exceptions on ipdb exit

[telamonian]

fixes:

• exiting an interactive ipdb session always raises/prints into cell output an unhandled BdbQuit exception jupyterlab/jupyterlab#12501

refs:

• protect IPython from bad custom exception handlers #876
• Improving recursive Pdb #1273
• BdbQuit exception when quitting ipdb #4474
• Notebook and qtconsole: ipdb.set_trace() not displayed properly #5306
• Simplify debugger classes. #9731
• Allowing debugging with -m IPython.terminal.debugger #9942
• enable quitting for -m IPython.terminal.debugger #9950
• impossible to exit debugger traces #10006
• Custom traceback not working as documented #12378

BdbQuit is now handled in the top-most scope of InteractiveShell.run_code. This ensures that BdbQuit is correctly handled but can still do its job of breaking out of all user code/loops/further breakpoint requests. Hopefully will work better than previous attempts, which put the BdqQuit handling in Pdb.set_trace.

In terms of ipdb integration with the jlab UI, it's a big improvement.

Before:

After:

Much less noisy

pinging @Carreau for a review

[telamonian]

I also tested to make sure that the change in this PR is compatible with the work done in #9942 and #9950 to enable running terminal.debugger as main, eg:

python -m IPython.terminal.debugger testDebug.py

and it seems to be compatible. However, there were other strange problems relating to imports that did keep the python -m <some debugger> ... stuff from working. I was able to work around those issues by shuffling some imports from top level to under the TerminalPdb class scope. It's out of scope for this PR, tho, so I'll open a new issue about that

[Carreau]

really all these should be in your gitignore global:

https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files

[Carreau]

@meeseeksdev backport to 7.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 7.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 1893a8f59482626cf3a20ea7dd63379d97c026ea

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #13668: fix uncaught `BdbQuit` exceptions on ipdb `exit`'

4. Push to a named branch:

git push YOURFORK 7.x:auto-backport-of-pr-13668-on-7.x

5. Create a PR against branch 7.x, I would have named this PR:

"Backport PR #13668 on branch 7.x (fix uncaught BdbQuit exceptions on ipdb exit)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.