[MVUX][Navigation] Support for passing IFeed<T> instead of T into ViewModel

[nickrandolph]

What would you like to be added:

Two scenarios for passing data into a viewmodel:

• you have an entity of T, so the entity gets sent during navigation
• you have the id of T, so need to look up (retreive) T, before sending it via navigation In both scenarios the target viewmodel should ideally receive Feed<T> - this way if a service needs to be called to retrieve T, it can be done asynchronously

Why is this needed:

Async lookup for T would mean that navigation is faster, and that any loading indicator is shown on the target view.

For which Platform:

• [ ] iOS
• [ ] Android
• [ ] WebAssembly
• [ ] WebAssembly renders for Xamarin.Forms
• [ ] Windows
• [ ] Build tasks

Anything else we need to know?

[agneszitte]

@nickrandolph, @dr1rrb is this one still a priority? (cc @eriklimakc as you will be helping with Navigation documentation)