Add \SMW\SPARQLStore\TurtleTriplesBuilder

- Move code from `SparqlStore` into its own `TurtleTriplesBuilder` component
I think the following change can fix that:
https://github.com/nischayn22/SemanticMediaWiki-1/commit/fd48c01c62c11ef41aca05ecdf74fa1a796f93b6