[MBL-1491] [MBL-1663] Handle 3DS authentication with informational snackbar

[stevestreza-ksr]

📲 What

This PR adds support for letting a user handle 3DS authentication via Stripe.

🤔 Why

Stripe won't process some transactions otherwise.

🛠 How

When the user taps the "authorize card" button, I added a loading indicator to the button and updated the enum cases to include a way to turn that loading indicator off.

Then I added fetching the client secret from GraphQL and passing that through the enum case for triggering 3DS authentication.

With those pieces in place, I updated PPOViewModel to call Stripe's authentication check. In debug mode, this is simulated for ease of testing. When the callback completes, the app informs the user that the call has either succeeded or failed. This was done with a touched up version of the MessageBannerView that already existed and had some basic hookups in the PPOViewModel.

If successful, the item is hidden. This was done by adding filtering capability to PPOViewModel and tying it to the existing Publisher chain for populating results.

I also added some convenience helpers for clarity, such as withEmptyValues() on Publisher, a pattern that I was using in a few places, and a way to map the values of a Paginator's Results (in this case, to facilitate filtering).

👀 See

Figma

✅ Acceptance criteria

Tests should pass.

End-to-end testing should succeed.

[amy-at-kickstarter]

LGTM.

I have some thoughts/suggestions/nits/discussions, but nothing that's blocking.

[ifosli]

I like the banner changes - very nice! I am concerned about this approach to 3DS - I know we talked about the complication with where to present what (considering banners) before, but it feels weird to me to have a view model presenting UI instead of a view controller. I trust your judgement, though. But I do think it'd be helpful to test this end to end now, while you still have alternatives fresh in your mind, in case the 3DS UI doesn't get presented correctly or something.

[nativeksr]

	1 Warning
⚠️	Big PR

SwiftFormat found issues:

File	Rules
Kickstarter-iOS/Features/PledgedProjectsOverview/PPOContainerViewController.swift:181:1	warning: (blankLinesAtStartOfScope) Remove leading blank line at the start of a scope.
Kickstarter-iOS/Features/PledgedProjectsOverview/PPOContainerViewController.swift:227:1	warning: (unusedArguments) Mark unused function arguments with _.

Generated by 🚫 Danger

[amy-at-kickstarter]

LGTM! I like the refactor. A couple non-blocking nits and commentary.