Allow aggregate_profiles to exclude single cloudy profiles

[martin-rdz]

As discussed multiple times...

[martin-rdz]

I came up with an initial try for omitting single cloudy profiles. The solution is not extremely elegant, but minimizes interference with exisiting code.

The approach is to manually define a clFreeGrp that contains a cloud, if needed modify flagCloudFree, and aggregate with aggregate_profiles(flagVal=True).
A working example is included in tests/test_case_cpv_2024-08-21_exclude_clouds.ipynb.

Switching between data_cube.aggregate_profiles() and data_cube.aggregate_profiles(flagVal=True) produced both of the aggregated profiles