Read weather data from smartspace extras

Also, rename Weather class to WeatherData.

To enable weather data, run:

  adb shell device_config put device_personalization_services \
          EchoSmartspace__enable_weather_data_extras true
Test: atest SystemUITests:LockscreenSmartspaceControllerTest
Test: Attach debugger and read values
Bug: 265069396

Change-Id: I800703be0af19e352542919c8cbb8bfa4ccb9932