Move UidRange to connectivity

UidRange is a data class that is an implementation detail of
Connectivity. Move it to the connectivity boundary.

Remaining usages of UidRange outside of Connectivity (in VPN) should be
migrated to other classes, like Range<Integer> or UidRangeParcel.

Bug: 181512874
Test: m
Change-Id: I6f2e3685ad1c07171dd90480d1e546329de8732d