feat: implement except operator

doc/sql/feature_taxonomy.md

src/executor/bucket.rs

src/executor/bucket/tests.rs

src/executor/engine/cartridge/backend/sql/ir.rs

src/executor/engine/cartridge/backend/sql/ir/tests.rs

src/executor/engine/cartridge/backend/sql/tree.rs

src/executor/ir.rs

src/frontend/sql.rs

src/frontend/sql/ast.rs

src/frontend/sql/query.pest

src/ir/distribution.rs

src/ir/explain.rs

src/ir/expression.rs

src/ir/operator.rs

src/ir/operator/tests.rs

src/ir/transformation/redistribution.rs

src/ir/transformation/redistribution/tests.rs

src/ir/transformation/redistribution/tests/except.rs

src/ir/tree.rs

test_app/test/integration/api_test.lua