Compatibility of ep.pp.simple_impute with different array types

[eroell]

Description of feature

Follow the template workflow of #835:

• [ ] introduce singledispatch to check for allowed data types, or raise an error if others are encountered
• [ ] adapt the tests to check these data types

[eroell]

This can help for Dask: https://ml.dask.org/modules/generated/dask_ml.impute.SimpleImputer.html

[eroell]

Close in favor of #945