feat: support trim function

doc/sql/query.ebnf

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

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

sbroad-core/src/frontend/sql.rs

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

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

sbroad-core/src/ir/aggregates.rs

sbroad-core/src/ir/explain.rs

sbroad-core/src/ir/expression.rs

sbroad-core/src/ir/function.rs

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