[migration/pdb] display traceback instead of only the exception for easier debugging Closes #17219820

[migration/pdb] add option to use pdb.post_mortem if traceback is provided Post mortem is a mode where the pdb shell is opened **where** the exception as occured instead at the breakpoint for set_trace. This is way more useful for debugging for the user because is will have the full context of the error. Closes #17219827

[migration/shell] select ipdb if present on (d)ebug mode Closes #17219833