Add parameterized ViewModel injection via factories

[adriangl]

PR's key points

The PR adds support for injecting ViewModel factories and for retrieving ViewModels via previously declared factories. This will ease parameterized ViewModels delivery and remove some boilerplate that we use when configuring the ViewModels in production code.

The added code relies in a new TypedViewModel that enforces passing a single params value to ensure type safety in the injection functions.
I couldn't think of a better idea to do this, so if you have any other ideas (the ideal thing would be to ensure type safety while also not forcing to extend another class) feel free to propose them 😉

The final idea would be:

• Create your ViewModel with parameters.
• Create a ViewModelProvider.Factory that creates said ViewModel. Since the code wouldn't be especially complex, we can use something like https://github.com/radutopor/ViewModelFactory to auto-generate said factories and save some boilerplate.
• Inject the ViewModelProvider.Factory with bindViewModelFactory
• Retrieve a ViewModel instance with parameters using by viewModel(parameters)