from_imod5_data should support period boundary conditions (e.g. Summer & Winter)

[JoerivanEngelen]

• The project file contains a summer and winter stage. This creates a periodic boundary condition. These are usually applied to iMOD5's RIV and DRN package. We can imitate that behaviour with the repeat_stress settings.

• The open_projectfile_data function collects the repeat stresses in a separate dictionary. This is the second element of the returned tuple. https://github.com/Deltares/imod-python/blob/7e948503a48cc4750f6d350a78ac3b4d3590918a/imod/formats/prj/prj.py#L942

• Each periodic boundary conditions has its own entry in this dictionary

• To create repetitions, we can utilize this helper function: https://github.com/Deltares/imod-python/blob/7e948503a48cc4750f6d350a78ac3b4d3590918a/imod/formats/prj/disv_conversion.py#L686

• Demarcation for now: Throw error if any other boundary condition package than GHB, RIV or DRN is periodic.

[JoerivanEngelen]

The GRAM 3.1 projectfile provides example data for summer/winter stage, for both the drains as well as rivers. Drains are the simplest example, as there is only one system allocated.