*move the tests from `datafusion/sql/src/planner.rs` into `datafusion/sql/test/planner.rs` or similar to help parallelize the test compilation* from https://github.com/apache/arrow-datafusion/pull/4783#pullrequestreview-1233427939
move the tests from
datafusion/sql/src/planner.rsintodatafusion/sql/test/planner.rsor similar to help parallelize the test compilationfrom #4783 (review)