Reminder user of unavailable tethering status if there is no internet access. Bug: 147818698 Test: atest TetheringTests Change-Id: Ic6557f9f7703337596100cd6a477fd7239217166 Merged-In: Ic6557f9f7703337596100cd6a477fd7239217166 (cherry picked from commit ac1b098acc504b60e85b3dcd22941f4e293865ae, aosp/1237036)