arch.<arch>.deps now works in android_filesystem

android_filesystem is a multi targets module type inhering from
PackagingBase. Since it's a multi-targets module, it is mutated only for
the common arch and therefore arch-specific properties are NOT squashed
into the matching top level property (i.e. setArchProperties is no op).

As a result, the values set in arch.<arch>.deps property were ignored.

This fixes the issue by explicitly adding the properties in
arch-specific structs and reading the properties in the matching arch.

Also added a set of tests for non-multi-target modules.

Bug: N/A
Test: m
Change-Id: Ibd4b509e73fa1760cc38b3661a08f83a6f639705