Replace Failure._findFailure dependency on bytecode with some mechanism that doesn't rely on bytecode #12288
Description
The problem:
- As seen in Fix inlineCallbacks tests on Python 3.13 #12061, changes to generated bytecode can break
Failure's specialinlineCallbacksrelated code(and quite possibly async functions too). - In a world where a CPython JIT is a possibility, it's not clear if any of this will work at all in the future.
It would be better to have a mechanism for finding the current failure that is less tied to obscure implementation details of Python. Perhaps contextvars might do the trick?