* Create query_obj for every filter
* Deprecate is_prequery and prequeries from query_obj
* Fix tests
* Fix typos and remove redundant ; from sql
* Add typing to namedtuples and move all query str logic to one place
* Fix unit test
* fix(sql-lab explore): fixed response data and header type to be aligned
* fix(sql-lab explore): fixed test error caused by incorrect test at master
* fix(sql-lab explore): reformatted
* fix(sql-lab explore): removed unused import