Mark ParsedConfiguration.parsedInfo as @Nullable

The ParsedConfiguration.parsedInfo field is marked as @NonNull, but in
case the parsed configuration originated from an overlay config file (as
opposed to the legacy manifest based approach), the field will be null.
Change the field from @NonNull to @Nullable to reflect this.

Bug: N/A
Test: builds
Change-Id: I4119712a65d0f7c6caf2b4810457aeaa05eb2777