Move a few packages from core_minimal.mk to base.mk.

All the products that inherit from base.mk add these packages, so moving
them up the hierarchy eliminates some duplication.

        DownloadProvider
        idmap
        libneuralnetworks
        mdnsd
        MediaProvider

Bug: 80410283
Test: diff all product variables with multiproduct_kati
Change-Id: I133a385b3bc64261d73f616c416f7a905675c09d