[Sample] How to set a VM to a UserControl

[agneszitte]

Discussed in unoplatform/uno#17032

Question from @ArchieCoder: in the reference samples that use MVVM, all the samples have pages with its corresponding VM. This works well with RouteMap + Navigation system. If I have a page that is more complex with some UserControls. If I want to have a VM for a UserControl. What is the trick to create a VM that resolves the dependencies in the constructor?

We should create a quick sample demonstrating the use of a UserControl-specific ViewModel (VM) with Dependency Injection (DI) and Binding, within the context of a parent ViewModel.
(See more details in the related discussion: unoplatform/uno#17032 and Discord thread).