base: add hooks to backup and restore omni settings

for heavens sake google...
dont force us to change both Settings and SettingProvider for
every setting we add and want to be backed up

[micky387] edit with OmniSettings changes

Change-Id: Id6c8a7183d5a008ca7fd38ea4042046ab3168ec5
diff --git a/packages/SettingsProvider/Android.bp b/packages/SettingsProvider/Android.bp
index 75f8384..70ce189 100644
--- a/packages/SettingsProvider/Android.bp
+++ b/packages/SettingsProvider/Android.bp
@@ -37,6 +37,7 @@
         "aconfig_demo_flags_java_lib",
         "device_config_service_flags_java",
         "libaconfig_java_proto_lite",
+        "OmniLib",
         "SettingsLibDeviceStateRotationLock",
         "SettingsLibDisplayUtils",
     ],