clean up OverriddenWarnigsDao

OpenKeychain/src/main/sqldelight/org/sufficientlysecure/keychain/OverriddenWarnings.sq

@@ -1,4 +1,16 @@
 CREATE TABLE IF NOT EXISTS overridden_warnings (
     _id INTEGER PRIMARY KEY AUTOINCREMENT,
     identifier TEXT NOT NULL UNIQUE
-);
+);
+
+selectCountByIdentifier:
+SELECT COUNT(*)
+    FROM overridden_warnings
+    WHERE identifier = ?;
+
+insertIdentifier:
+INSERT OR IGNORE INTO overridden_warnings (identifier) VALUES (?);
+
+deleteByIdentifier:
+DELETE FROM overridden_warnings
+    WHERE identifier = ?;