Support querying rdf repository
- Implemented query method
- Renamed and updated query payload class. Now it is QueryPayload and holds query parameters plus additional configurations needed for proper request execution and parameters validation.
- Deleted update-query class - TBD: maybe we should introduce it later again!
- Fixed exporting of QueryType
- Added QueryLanguage enum
- Implemented tests for QueryPayload
- Implemented tests for the new repository#query method
- Introduced new third party library for mocking nodejs streams