Convert location settings to DashboardFragment.

- change LocationMode, LocationSettings, and ScanningSettings to be
DashboardFragment.
- remove LocationSettingsBase and moved base logics into base
controller.
- add controllers for the preferences under the 3 location settings
pages.

Fixes: 68719207
Test: make RunSettingsRoboTests
Change-Id: Icedf691c2a9f7989faebee39ea9da672209b7957

tests/robotests/src/com/android/settings/location/ScanningSettingsTest.java

@@ -34,13 +34,12 @@ import org.robolectric.annotation.Config;
 import java.util.List;
 
 @RunWith(SettingsRobolectricTestRunner.class)
-@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION_O)
 public class ScanningSettingsTest {
 
     private Context mContext;
     private ScanningSettings mSettings;
 
-
     @Before
     public void setUp() {
         mContext = RuntimeEnvironment.application;