AddLoadHookWithPriority function in build/soong/android

This is a wrapper around `AddLoadHookWithPriority` in build/blueprint,
and allows users to add a load hook at a specified priority.

One use case for this is to defer autogenerated rro creation load hook
of override_android_app

Test: m nothing --no-skip-soong-tests
Change-Id: Ib0f6cbcb87099700df4dfcc1d6af740f96c419e9