Experiment: using xeus-python-kernel to improve performance

I found xeus-python-kernel https://xeus-python.readthedocs.io/en/latest/ when checking approaches to improve the performance of the voila app up about 8% loading time.
It is a lightweight python-kernel that as an alternative for the `ipykernel` to gain more performance.
In principle, we can use it for all apps in aiidalab.