feat: implement data sharding on the executor side

benches/engine.rs

benches/parse.rs

src/executor.rs

src/executor/bucket.rs

src/executor/bucket/tests.rs

src/executor/engine/cartridge.rs

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

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

src/executor/engine/mock.rs

src/executor/ir.rs

src/executor/shard.rs

src/executor/tests.rs

src/executor/vtable.rs

src/executor/vtable/tests.rs

src/ir/helpers.rs

src/ir/transformation/helpers.rs