Ipyexperiments

-

- add CUDA_MODULE_LOADING=EAGER to force CUDA kernel preloading
- drop the no-longer working pytest-ipynb, and switch to nbmake for testing

- fix implicit imports
- fix `ipyexperiments.utils.ipython.ipython_tb_clear_frames`

- skipped

- get rid of the attempt to use the backend methods in the cell logger, too many deadlock issues - just use pytorch for now if available and remove the pointless abstraction (needs more cleanup)
- completely rewrite general RAM reporting as I discovered tracemalloc can't track non-python application, so general RAM reporting was completely invalid at times. Switch to the same approach as pynvml tracking, with a thread to monitor peak memory usage.
- simplify the logic of how gpu peak memory is calculated
- fix broken tests now that RAM is reported correctly
- improve logging format

- fix preload_pytorch to load the 0th device by default
- fix the test suite with CUDA_VISIBLE_DEVICES=0 CUDA_DEVICE_ORDER=PCI_BUS_ID to that cuda and pynvml report the same gpus
- `preload_pytorch` is no longer automatically run in ipyexperiments.utils.mem - as it may interfere with other systems. it's an explicit call now.