[mlir] Add `Print(Attr|Type)Qualified` trait

This PR adds a new trait to attributes and types that force the use of the qualified syntax for attributes and types. More concretely, any attribute or type with the trait must be parsed and printed with the `dialect.mnemonic` prefix.

The motivation for this PR is the dependent PR where it is used to retain backwards-compatibility of syntax, but downstream projects may also use the trait if the subjectively prefer the verbose syntax.