Add a `qualified` directive to the Op, Attribute, and Type declarative assembly format

This patch introduces a new directive that allow to parse/print attributes and types fully
qualified.
This is a follow-up to ee090870 which introduces the eliding of the `!dialect.mnemonic` by default and allows to force to fully qualify each type/attribute
individually.

Differential Revision: https://reviews.llvm.org/D116905