Duplicate code: QueryBindingSet and SPARQLQueryBindingSet should be replaced by a generic implementation

[abrokenjester]

(Migrated from https://openrdf.atlassian.net/browse/SES-1773)

{{QueryBindingSet}} in {{queryalgebra-evaluation}} is an almost line-for-line duplicate of {{SPARQLQueryBindingSet}} in {{repository-sparql}}. The former project has a compile dependency on the latter. So a version, possibly using generics, should replace both of them in {{repository-sparql}}.