[MBL-1355] Move Login/Signup Logic To Confirm Pledge Details

[scottkicks]

📲 What

Addresses MBL-1347 issue by moving login/signup logic from PostCampaignCheckoutViewController to ConfirmDetailsViewController

🤔 Why

By gating the checkout screen and checkout id creation behind login/signup, we can keep UX much simpler and more straightforward for users and code perspective.

🛠 How

1. Remove login logic from PostCampaignCheckoutViewController
2. Add the same login logic to ConfirmDetailsViewController but attach to continue button tap.
3. Call .createCheckout only if the user is logged in. The same goes for navigating to checkout. Users should never reach that screen if they aren't logged in.
4. Navigating back to Confirm, from Checkout, should create a new checkout ID and should all for successful late pledging.

👀 See

Simulator.Screen.Recording.-.iPhone.15.Pro.Max.-.2024-04-08.at.12.06.42.mp4

✅ Acceptance criteria

Original test scenarios that were failing

• Login is presented after tapping continue on ConfirmDetails Screen if logged out
• Users can not reach the Checkout screen if logged out
• if logged in users can confirm pledge details and complete late pledge flow successfully. This is true even if users navigate back and forth around the late pledge flow.

[scottkicks]

At first glance, it looks like LoginToutViewController doesn't actually use the project or reward being passed in, but I found that they're specifically for analytics.

[amy-at-kickstarter]

I've noticed this in quite a few places - a a view model requiring way more information than seems initially necessary, because it gets passed through to analytics. This is something we might consider for future refactoring. The way we pass around "contexts" in some places feels like a better model for this.

[ifosli]

Code looks good! I still think we should fix the "user needs to tap continue twice" to log in and proceed to the checkout page, but I'll let you decide if that's something you have time to do in this pr or not, since it's release-blocking.

[amy-at-kickstarter]

Nit: It would be good to throw an assertion in this view model to this effect.