Change String to SmolStr in sbroad-core/

sbroad-core/src/executor.rs

sbroad-core/src/executor/engine/helpers.rs

sbroad-core/src/executor/engine/helpers/storage.rs

sbroad-core/src/executor/engine/helpers/storage/runtime.rs

sbroad-core/src/executor/ir.rs

sbroad-core/src/executor/protocol.rs

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

sbroad-core/src/frontend/sql.rs

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

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

sbroad-core/src/ir.rs

sbroad-core/src/ir/acl.rs

sbroad-core/src/ir/block.rs

sbroad-core/src/ir/ddl.rs

sbroad-core/src/ir/transformation/redistribution.rs

sbroad-core/src/ir/transformation/redistribution/groupby.rs