[linkis-gateway-core]module errorcode optimization and documentation
Example:
documentation(文档)

Error code optimization(错误码优化)

Classes that need to be optimized(需要优化的类)
| class |
path |
| GatewayErrorException |
org.apache.linkis.gateway.exception.GatewayErrorException |
| TooManyServiceException |
org.apache.linkis.gateway.exception.TooManyServiceException |