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