Store ETWS primary information in the database

ETWS primary/secondary flag needs to be saved in the
database in order to perform duplicate check later. Used the
hardcoded database column name because Android R API freezes.
Will remove the hardcode in the next Android release.

Fix: 157699377
Test: CtsTelephonyTestCases & CellBroadcastServiceTests
Change-Id: Iedec92a1f435f60ceb9f36637a1718adbbd7e2ae