add grouping by cols

sbroad-cartridge/src/cartridge/router.rs

sbroad-cartridge/src/cartridge/storage.rs

sbroad-cartridge/test_app/test/data/config.yml

sbroad-cartridge/test_app/test/integration/api_test.lua

sbroad-cartridge/test_app/test/integration/groupby_test.lua

sbroad-core/src/backend/sql/ir.rs

sbroad-core/src/backend/sql/tree.rs

sbroad-core/src/executor/bucket.rs

sbroad-core/src/executor/bucket/tests.rs

sbroad-core/src/executor/ir.rs

sbroad-core/src/executor/tests.rs

sbroad-core/src/executor/tests/subtree.rs

sbroad-core/src/executor/vtable.rs

sbroad-core/src/frontend/sql.rs

sbroad-core/src/frontend/sql/ast.rs

sbroad-core/src/frontend/sql/ast/tests.rs

sbroad-core/src/frontend/sql/ir.rs

sbroad-core/src/frontend/sql/ir/tests.rs

sbroad-core/src/frontend/sql/query.pest

sbroad-core/src/ir.rs