Fix issue where existing Activity Resources references would not update

When relaunching an Activity, the DecorView and ViewRootImpl is re-used,
along with the IBinder activity token. This means that when we create
new resources, we end up just updating the base Activity resources.

However, we would set the configuration to the new requested override
config and then proceed to update existing Resources references, which
would return immediately due to the equality check for configuration
updates.

This change pushes the setting of the new override config to the
updateResourcesForActivity method, which will properly update Resources
references that are held in the re-used DecorView.

Bug:27915587
Change-Id: I113007a40fa464b8a234b073dcf851e16fee0177