Add official Signal support to *ng-mocks*.

[ytchenak]

Signals are the future of Angular, and if ng-mocks doesn't adapt to this trend, it risks becoming irrelevant. Currently, ng-mocks lacks support for Angular's official Signals. While it may function in some cases due to the Angular compiler mimicking @Input and @Output behavior when Signals are used, there are known issues like #10942, and potentially more.

Moreover, there are no unit tests for Signal scenarios, and we're unable to create them because ng-mocks doesn't utilize the same builder as modern Angular. When trying to create Signal components, the compilation fails since ng-mocks' build process doesn't generate the necessary @Input, @Output metadata from Signal input(), output(), and model() functions.

[Dji75]

There are already lots of workarounds working to handle input/ouput/model/viewchild/contentChild signals (I didn't checked for the two last ones but I already used those for the first ones).

But anyway, agree we would have a proper solution.