This patch makes it possible to use the newly added useDefaultAttributePrinterParser and useDefaultTypePrinterParser dialect options without any using namespace declarations. Two things had to be done to make this possible: * Fully qualify any type usages or functions from the mlir namespace in the generated C++ code * Makes sure to emit the printers and parsers inside the same namespace as the Dialect Differential Revision: https://reviews.llvm.org/D114168