Implement get_creation_statistics for QB with SQLite backend

[GeigerJ2]

Just realized here that get_creation_statistics is not implemented for the sqlite backend. So this is still missing for full feature parity.

In test_querybuilder.py, from the marker pytest.mark.requires_psql and the comment in the code "fails with sqlite with: sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such function: date_trunc" it seems like a custom implementation could be required again.

Possibly nice to include in v2.7, to promote full feature parity between the SQL backends (apart from limitations to concurrent writes of SQLite @agoscinski).