[choir] Rid off from any context reference in the view models

[Gelassen]

User story

As a user I want to have a high quality app

Tech details

There are several places where context has been passed inside view model. It was done to speed-up prototyping and mostly used to provide reference to R.string. When it might ok for a quick prototyping, it is not good for a production app. Reference on the context inside viewmodel is a potential memory leak and should be avoided.

As a part of this ticket look at other areas of code that should be improved.

[Gelassen]

Reference to context has been removed. However, some ViewModels extends AndroidViewModel which by itself requires application as a constructor parameter. To use it is a safe. It might be a solution for a future similar scenarios.

Issue has left open because it would be used for the rest request for refactoring and rising up app quality.