Add Id to ImageResource mapper

[ataulm]

fun idToImageResource(id: Int) = ImageResource.Builder()
       .setAndroidResourceByResId(
               AndroidImageResourceByResId.Builder()
                       .setResourceId(id)
                       .build()
       )
       .build()

From here:

https://github.com/joreilly/PeopleInSpace/pull/139/files#diff-4058974ed1ff8fbb817967ab294ee5a8b422543b015c50cf3481cc2fddffbe0cR119-R126

I'm using it for a component audit (in combination with LayoutPreview) but presumably it's handy for the tile renderer too.

Notes:

• consider adding @DrawableRes to the function

[yschimke]

+1 to DrawableRes. Also as an extension function on Resources.Builder, it should show up magically inside the Preview blocks and so on.

[yschimke]

Adding in #235