Paywalls: disable the close button when an action is in progress (#3474)

Disabled and lowered the opacity of the close button while an action is
in progress, to prevent a potentially bad UX state when you exit the
paywall.

RevenueCatUI/PaywallView.swift

@@ -309,7 +309,7 @@ struct LoadedOfferingPaywallView: View {
  if let dismiss = self.dismiss {
  NavigationView {
  view
- .toolbar { Self.toolbar(dismiss) }
+ .toolbar { self.toolbar(dismiss) }
  }
  .navigationViewStyle(.stack)
 
@@ -329,13 +329,18 @@ struct LoadedOfferingPaywallView: View {
  )
  }
 
- private static func toolbar(_ dismiss: @escaping () -> Void) -> some ToolbarContent {
+ private func toolbar(_ dismiss: @escaping () -> Void) -> some ToolbarContent {
  ToolbarItem(placement: .destructiveAction) {
  Button {
  dismiss()
  } label: {
  Image(systemName: "xmark")
  }
+ .disabled(self.purchaseHandler.actionInProgress)
+ .opacity(
+ self.purchaseHandler.actionInProgress
+ ? Constants.purchaseInProgressButtonOpacity
+ : 1)
  }
  }