[MBL-2110] [MBL-2113] Fixes for PPO analytics events

[stevestreza-ksr]

📲 What

Two fixes:

1. Make sure that analytics events are only firing once; if the page reloads, they currently send all events another time.
2. Add a missing event for the user tapping "confirm" on the confirm address popup

🤔 Why

1. In order to support the counts properties we need, we use Combine to grab the most recent results from the Paginator. However, when the user pulls to refresh, this causes the Paginator's results publisher to fire again, triggering all analytics events a subsequent time.
2. This event was added but never connected.

🛠 How

1. Instead of using combineLatest, this was changed to a flatMap + first. This causes the Paginator's results method to fire immediately, and only one time. Since this is a flatMap, this process repeats every time the flatMap happens (e.g. every time the relevant button is clicked). This gets us the behavior we need.
2. The analytics for PPO are handled in PPOViewModel, but the confirm address button happens in the PPOContainerViewModel. So to support this, I added a PPOActionState closure to the confirmAddress case, similar to 3DS, and listen to it in the PPOViewModel. This also needed a new case added to PPOActionState, confirmed, when the user has confirmed their intent but processing is still happening.

[amy-at-kickstarter]

I've got two non-blocking suggestion for making this more self-documenting - but the fix itself LGTM.

Thanks for the excellent explanation in the review notes!