Deprecate get_totals_for_[qualifier|property] to use generalized queries

We have been dealing with too many methods doing similar SPARQL querying,
while we could unify their structure and use polymorphism.

In a previous commit, get_totals_query was moved to ColumnConfig,
to be used by PropertyConfig (on top of TextConfig).

• Add get_filter_for_info to PropertyConfig
• Remove isinstance dance in make_footer, instead use polymorphism and get_totals_query from ColumnConfig
• Remove get_totals_for_property and get_qualifier_for_property, as well as their unit tests
• Add tests for the various possiblities of get_totals_query.