Refactor android/paths.go to allow reuse

Extracts out the relevant pieces of ModuleContext into a minimal
interfaces necessary for path handling for Modules. This will allow
reuse in queryview by allowing it to implement only the parts of the
module interface necessary for path expansion in order to properly
handle path properties.

Test: go test soong tests
Change-Id: Iea39a365e5a2ff55071e435fb64f9e6464bbcafd