refactoring: make more readable error for parsing schema

.luacheckrc

Makefile

sbroad-cartridge/Makefile

sbroad-cartridge/cartridge/roles/sbroad-router.lua

sbroad-cartridge/cartridge/roles/sbroad-storage.lua

sbroad-cartridge/src/api/helper.rs

sbroad-cartridge/src/cartridge/config.rs

sbroad-cartridge/src/cartridge/config/tests.rs

sbroad-cartridge/src/router.lua

sbroad-cartridge/src/storage.lua

sbroad-cartridge/test_app/test/helper.lua

sbroad-cartridge/test_app/test/integration/api_test.lua

sbroad-cartridge/test_app/test/integration/ddl_test.lua

...rtridge/test_app/test/integration/target_queries_test.lua

...tridge/test_app/test/integration/validate_schema_test.lua

sbroad-core/src/errors.rs

sbroad-core/src/ir/relation.rs