API Review: TetherNetwork, DeviceInfo

Renamed TetherNetwork to HotspotNetwork and replaced all usage
of Tether with Hotspot.
Renamed DeviceInfo to NetworkProviderInfo.
Added DEVICE_TYPE_WATCH and DEVICE_TYPE_AUTO for futureproofing
in NetworkProviderInfo.java

Bug: 268486125
Test: atest (all affected test classes)

Change-Id: I889457f02322644f3779bf25c3a125f7f973c69c