…ssing on asyncio, though not necessarily for good reasons

…st passing

…rk with which library, and minor updates. 102/103/104 now sees asyncio.exceptions.CancelledError as a critical exception. Fix import/arg detection of asyncio. add asyncio102_asyncio. add async103_all_imported. Finally make test_anyio_from_config autodetect the correct line number. Fix BASE_LIBRARY marker being interpreted as a bool. Make #NOTRIO/#NOASYNCIO/#NOANYIO run the visitor but ignore the result, instead of skipping, to check it doesn't crash. Generalize error-message-library-check.

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>