notifications: make update alerts non-persistent

once acked, they remain acked. no need to keep nagging the user about them.

src/notifications.js

@@ -225,25 +225,26 @@ async function backupFailed(eventId, taskId, errorMessage) {
 }
 
 // id is unused but nice to search code
-async function alert(id, title, message) {
+async function alert(id, title, message, options) {
     assert.strictEqual(typeof id, 'string');
     assert.strictEqual(typeof title, 'string');
     assert.strictEqual(typeof message, 'string');
+    assert.strictEqual(typeof options, 'object');
 
     const result = await getByTitle(title);
 
-    if (!result) {
-        return await add(title, message, { eventId: null });
-    } else {
-        await update(result, {
-            eventId: null,
-            title,
-            message,
-            acknowledged: false,
-            creationTime: new Date()
-        });
-        return result.id;
-    }
+    if (!result) return await add(title, message, { eventId: null });
+    if (!options.persist) return result.id;
+
+    await update(result, {
+        id: result.id,
+        eventId: null,
+        title,
+        message,
+        acknowledged: false,
+        creationTime: new Date()
+    });
+    return result.id;
 }
 
 // id is unused but nice to search code