Start tethered hotspot with TetheringRequest

Use WifiManager.startTetheredHotspot(TetheringRequest, Executor,
SoftApCallback) to start softap. This allows for passing in the
requested SoftApConfiguration via TetheringRequest.

Bug: 216524590
Test: atest TetheringTest TetheringManagerTest
Change-Id: Ie4fb851e8b2243d233f9a8b3e18e2fa335cec307
4 files changed