Support access to resources (Colors, images..) using folder name spaces

[hadiidbouk]

Currently, resources cannot be accessed from the assets folder when they are inside a namespace folder.
We need to remove all the folders and use more verbose names.

For example, the code below will work on iOS, but on Android, the app crashes when calling it:

public static let primary = Color("Primary/DarkGray/300", bundle: .module)

This is a blocker for us, we already have the assets folder and we are using it in an iOS app, we cannot edit the structure to make it work with skip.

[marcprux]

It is true that Skip currently only supports "flattened" top-level resources. We'd like to expand this to support nested folders in the future, but we don't have an estimate yet for when that will be implemented.