Because of how name builders used to lazy gather namespaces on the first
requested name, the objects were self mutating. As such only non-const
references could be used to pass them around.
Since that is no longer the case, this restores most of lost const
qualifiers.
Not every case can benefit from extra liniency, so they were manually
reviewed on a case by case basis.
Additionally, this drops a couple of "this should be a non-strict
specialization" commits, because of a bug with clang
(see the GenericGraph concepts rework commit for more details) as
to avoid confusion (we wouldn't want anyone trying to solve these
"todo"s) until the clang struct type deduction is fixed. Especially
considering that there are currently no cases where these softer
versions would be beneficial (we never inherit from templates in
question).
By using this class we can create ptml::Tags without
XML tags. It is useful in the revng-c part when we
want to generate Plain C. All PTML Tags, from now on,
should be created via this class only.
In addition, port `Yield` library to be using this.
Giacomo Vercesi