Add turn on/off setting for Lychee in Contacts App.

1) User can turn on/off Lychee, or pick an account to backup and restore
contact metadata in Contacts App->Settings.
2) For now, this option is hidden.
3) When user turns Lychee on in Contacts App, set this account's
sync automatically as true and requestSync, others as false.

BUG 26491409

Change-Id: I063787f1465d965d43907ccc31fd0a7f102797e8
diff --git a/res-common/values/strings.xml b/res-common/values/strings.xml
index 17b21eb..6067eda 100644
--- a/res-common/values/strings.xml
+++ b/res-common/values/strings.xml
@@ -663,6 +663,9 @@
     <!--Label of the "default account" setting option to set default editor account. [CHAR LIMIT=80]-->
     <string name="default_editor_account">Default account for new contacts</string>
 
+    <!--Label of the "Contact metadata sync account" setting option to set sync account for Lychee. [CHAR LIMIT=80]-->
+    <string name="contact_metadata_sync_account">Contact metadata sync account</string>
+
     <!-- Label of the "About" setting -->
     <string name="setting_about">About Contacts</string>