In D6935 I made a mistake by `await`ing inside a loop. In order to `await` the `notifTextsForMessageInfo` in sequence, I'm going to extract the code inside the loop into its own `async` function.
`sendPushNotif` isn't exactly accurate, in the sense that it sends multiple... but `sendPushNotifs` is already the name of its caller. One alternative I considered was `sendPushNotifsForMessage`, but that's also slightly inaccurate because there might be multiple new messages. Open to alternatives (or votes for the latter name).