Show notification when READ_CONTACTS permission is denied in sync service, hide linked contact card if permission is denied

OpenKeychain/src/main/res/values/strings.xml

@@ -1505,6 +1505,8 @@
     <string name="account_no_manual_account_creation">"You can not create OpenKeychain accounts manually."</string>
     <string name="account_privacy_title">"Privacy"</string>
     <string name="account_privacy_text">"OpenKeychain does not synchronize your contacts with the Internet. It only links contacts to keys based on names and email addresses. It does this offline on your device."</string>
+    <string name="sync_notification_permission_required_title">"Linking keys needs contacts access!"</string>
+    <string name="sync_notification_permission_required_text">"Touch to configure linking to contacts"</string>
 
     <!-- Passphrase wizard -->
     <!-- TODO: rename all the things! -->