Bunch monitor

[eltos]

Für xsuite#504

@eltos ➜ /workspaces/xtrack (bunch-monitor) $ pytest tests/test_monitor.py::test_bunch_monitor
=================================== test session starts ===================================
platform linux -- Python 3.10.13, pytest-8.2.1, pluggy-1.5.0
rootdir: /workspaces/xtrack
configfile: pyproject.toml
plugins: anyio-4.4.0
collected 2 items                                                                                                                                                                                                                                                     

tests/test_monitor.py ..                                                             [100%]

=================================== 2 passed in 20.84s ====================================

Tests fehlen noch für zeta_mean, delta_mean, zeta2_sum, delta2_sum, zeta_std, delta_std, zeta_var, delta_var