Add NetworkStack to framework-connetivity and framework-tethering impl lib visibility am: e7cae17b3a am: 4ea3f01485

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3259762

Change-Id: I6ed8225ee99460b516ae2d26585e86681bfb2b67
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>