Move non-native cubit functionality out of wrapper

[isteinbrecher]

This moves all utility functionality out of the cubit host class. This makes the CubitConnect more of a pure wrapper.

[isteinbrecher]

@m-frey @knarfnitram @maxfirmbach

For now the functions get_geometry_type and get_node_ids are moved completely out of the Cubit class. Are these functions used by you? We could alternatively mode them to directly to CubitPy (not the wrapper), then nothing in the current behaviour of how to use CubitPy would change.

[knarfnitram]

I am using get_geometry_type, I would still like to use it or a similar function.

[isteinbrecher]

The functionality will definitely remain, the question is, if we want to have a free function

get_geometry_type(cubit, item)

or we want to add this as a method to the CubitPy object

cubit.get_geometry_type(item)

I think I would actually prefer the second variant (then no external workflows will notice this change), I will change that in this PR.

[isteinbrecher]

Maybe this is not so simple after all... I will try some solutions once I have some time and then push here. Likely we will have to change the interface of get_geometry_type and get_node_ids (slightly).