Support Taiwan Covid-19 free short code

Add 1922 as a free short code for Taiwan.
1922 sms is a new service announced in 05/19/2021 to streamline the mandatory contact tracing policy during pandemic in Taiwan.

BUG: 189442874
Test: ShortCodes are already in operation as tested.

Signed-off-by: Shawn Lien <shawnlien@google.com>
Change-Id: Ia62f8f9b4c2725109254153af5fdfc108f599dcb

core/res/res/xml/sms_short_codes.xml

@@ -245,6 +245,9 @@
     <!-- Slovakia: 4 digits (premium), plus EU: http://www.cmtelecom.com/premium-sms/slovakia -->
     <shortcode country="sk" premium="\\d{4}" free="116\\d{3}|8000" />
 
+    <!-- Taiwan -->
+    <shortcode country="tw" pattern="\\d{4}" free="1922" />
+
     <!-- Thailand: 4186001 used by AIS_TH_DCB -->
     <shortcode country="th" pattern="\\d{1,5}" premium="4\\d{6}" free="4186001" />