feature(plugin): add plugin SQL

doc/sql/query.ebnf

sbroad-cartridge/src/api/exec_query.rs

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

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

sbroad-core/src/executor.rs

sbroad-core/src/executor/ir.rs

sbroad-core/src/frontend/sql.rs

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

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

sbroad-core/src/ir.rs

sbroad-core/src/ir/api/parameter.rs

sbroad-core/src/ir/block.rs

sbroad-core/src/ir/distribution.rs

sbroad-core/src/ir/expression/types.rs

sbroad-core/src/ir/node.rs

sbroad-core/src/ir/node/plugin.rs

sbroad-core/src/ir/tree/expression.rs

sbroad-core/src/ir/tree/relation.rs

sbroad-core/src/ir/tree/subtree.rs