TAJO-1247: Store type 'TEXTFILE' should be TEXT while keeping enum 'TEXTFILE' in protobuf

Recently, we added TEXTFILE for all kinds line-delimited plan text files. But, its name is long and is different to naming convention that we've used. So, I propose renaming it to TEXT. But, TEXT is equivalent to the data domain 'TEXT', so we should keep its enum type in CatalogProtos.proto.