Kernel tests for xeus-cpp using Jupyter Kernel Tests

[kr-2003]

Kernel tests for xcpp are written here.
But as far as I remember, these tests were running in previous version of xeus-cpp. But now here are some of my findings:

• jupyter_kernel_test not properly integrated with xeus-cpp.

======================================================================
ERROR: test_kernel_info (__main__.CladXCppTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/site-packages/jupyter_core/utils/__init__.py", line 154, in wrapped
    asyncio.get_running_loop()
RuntimeError: no running event loop

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/site-packages/jupyter_kernel_test/__init__.py", line 62, in test_kernel_info
    reply = self.kc.get_shell_msg(timeout=TIMEOUT)
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/site-packages/jupyter_core/utils/__init__.py", line 158, in wrapped
    return loop.run_until_complete(inner)
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/asyncio/base_events.py", line 647, in run_until_complete
    return future.result()
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/site-packages/jupyter_client/client.py", line 143, in _async_get_shell_msg
    return await ensure_async(self.shell_channel.get_msg(*args, **kwargs))
  File "/home/abhinav/micromamba/envs/xeus-cpp/lib/python3.9/site-packages/jupyter_client/channels.py", line 232, in get_msg
    raise Empty
_queue.Empty

Something related to no async loop running.
2. But tests related to papermill works fine(notebook tests).

[kr-2003]

Also, I tried running it on MacOS(ARM64) built from source with same versions of llvm and clang(20.1.5). and in macos, all tests works perfectly fine.
The only problem is with ubuntu/linux based systems.