Move connectivity AIDLs to android.net

java_sdk_libraries and apexes need to contain bootclasspath classes
under predefined packages. Tethering currently uses android.net, so make
sure all the connectivity bootclasspath classes are under android.net.

This avoids maintaining two packages for the tethering APEX, where
com.android.connectivity.aidl is only used by internal AIDL files.

Bug: 182984842
Test: m
Change-Id: I611f1941698c574e37aea912ee76dadc8b32e41a