feat: support of multiple vshard groups

sbroad-cartridge/src/api/calculate_bucket_id.rs

sbroad-cartridge/src/cartridge/config.rs

sbroad-cartridge/src/cartridge/router.rs

sbroad-cartridge/src/init.lua

sbroad-core/src/core-router.lua

sbroad-core/src/executor.rs

sbroad-core/src/executor/bucket.rs

sbroad-core/src/executor/engine.rs

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

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

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

sbroad-core/src/executor/ir.rs

sbroad-core/src/frontend/sql.rs

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

sbroad-core/src/ir.rs