Support for treating qlalr warnings as errors during build

The suggestion is to provide the ability to treat qlalr warnings (eg. shift/reduce and reduce/reduce) as errors.

The rationale is to disallow warnings getting unintentionally in, by allowing CI / local build to prevent the successful build. This has been the case with Qt remote objects, where the warnings have gradually, over the years, crept into the parser grammar. Fixing them early on (or deliberately suppressing them) requires less effort than fixing them later.

I have not looked at all how to do that yet (cmake vs qlalr vs something else) so the current component is not the right one => identifying the component(s) will be part of this task.