Define parameter names convention and refactor

There are a lot of methods on the project that have the same parameter but using different names.

e.g, here are 3 different methods with the same parameter `@IdRes` using 3 different names:

`assertFocused(@IdRes resId: Int)`
`assertEndDrawerClosed(@IdRes id: Int)`
`assertRecyclerViewItemCount(@IdRes recyclerViewId: Int, expectedItemCount: Int)`

I think it will be a great idea to define a naming convention to keep the style while the project grows up

I know there's a lot of refactoring being done on the **barista2** branch, but I've already seen this on that branch