Propagate exceptions raised in Python callback functions

[madsbk]

Description

Currently, we ignore Python exceptions raised in callback functions called by resources such as CallbackMemoryResource. This is because Cython doesn't automatically translate Python exceptions into C++ exceptions (even though Cython does translate C++ exceptions into Python automatically).

To address this issue, we now translate Python exceptions raised in the callback function into a C++ exception manually. Next, we remove Cython's automatic C++ to Python exception translation by not using the except + declaration. Thus, when the callback raises an exception, the caller (a memory resource implemented in C++) can catch and/or propagate the exception.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[madsbk]

@bdice anything else needed here?

[vyasr]

One suggestion for improvement here, then I can approve. Bradley is out for most of this week.

[vyasr]

@gpucibot merge