Add a keywords for "Pair new deivce"

In new search version, our search won't show summary anymore.
So, we should add a new keyword so that search can find this
setting with "bluetooth" query.

Test: Rebuilt rom and see "Pair new device" in search
Fix: 15575560
Change-Id: I50b5ab10aafcab423f24341229f69c06b0176643

res/values/strings.xml

@@ -176,6 +176,8 @@
     <string name="bluetooth_empty_list_user_restricted">You don\u2019t have permission to change Bluetooth settings.</string>
     <!-- Title for bluetooth pairing item [CHAR LIMIT=60] -->
     <string name="bluetooth_pairing_pref_title">Pair new device</string>
+    <!-- Keywords for bluetooth pairing item [CHAR LIMIT=30] -->
+    <string name="keywords_add_bt_device">bluetooth</string>
 
     <!-- Bluetooth Visibility message.  This message informs the user that their device is now visible to other bluetooth devices.  [CHAR LIMIT=NONE] -->
     <string name="bluetooth_is_visible_message"><xliff:g id="device_name">%1$s</xliff:g> is visible to nearby devices while Bluetooth settings is open.</string>

res/xml/connected_devices.xml

@@ -43,6 +43,7 @@
         android:summary="@string/connected_device_add_device_summary"
         android:fragment="com.android.settings.bluetooth.BluetoothPairingDetail"
         settings:allowDividerAbove="true"
+        settings:keywords="@string/keywords_add_bt_device"
         settings:userRestriction="no_config_bluetooth"
         settings:useAdminDisabledSummary="true"
         settings:controller="com.android.settings.connecteddevice.AddDevicePreferenceController"/>