Consider redesign of SPARQLModelAdapter

[lu-pl]

An alternative and arguably better interface for SPARQLModelAdaper would be something like this:

adapter = SPARQLModelAdapter(
    endpoint="https://query.wikidata.org/bigdata/namespace/wdq/sparql",
    query=query,
    model=model
)

# -> Iterable[_TModelInstance]
adapter.query()

# -> dict[str, Iterable[_TModelInstance]]                                                                            
adapter.query_group_by("x")
                                                   
# -> dict[str, Iterable[_TModelInstance]]/Iterable[_TModelInstance] ; len == 50 + page/size info
adapter.query_paginate(page=1, size=50, group_by="x")  

This simplifies usage and splits the responsibilities of SPARQLModelAdapter.__call__ into separate specialized methods.

A first step would be to transfer SPARQLModelAdapter.__call__ to SPARQLModelAdaper.query.