Add service implementation for ThreadNetworkController#setEnabled

ThreadNetworkControllerService handles setEnabled requests and
asks ot-daemon to enable/disable Thread. The desired Thread enabled state
is saved in thread persistent setttings, the setting is loaded at bootup.

Bug: 299243765

Test: atest CtsThreadNetworkTestCases:android.net.thread.cts.ThreadNetworkControllerTest

Change-Id: Ifd0135433df25d9c6cfd3f365dd06ec7908268e7