Add accessibility label to purchase cells

PIALibrary/Sources/UI/iOS/PurchasePlanCell.swift

@@ -34,6 +34,8 @@ class PurchasePlanCell: UICollectionViewCell, Restylable {
         isSelected = false
         labelBestValue.text = L10n.Welcome.Plan.bestValue.uppercased()
         selectedPlanImageView.alpha = 0
+        self.accessibilityTraits = UIAccessibilityTraits.button
+        self.isAccessibilityElement = true
     }
     
     func fill(plan: PurchasePlan) {
@@ -57,6 +59,7 @@ class PurchasePlanCell: UICollectionViewCell, Restylable {
             labelPlan.text = plan.title
             labelDetail.text = plan.detail
             labelPrice.text = L10n.Welcome.Plan.priceFormat(plan.monthlyPriceString)
+            self.accessibilityLabel = "\(plan.title) \(plan.detail) \(labelPrice.text)"
             viewBestValue.isHidden = !plan.bestValue
             if viewBestValue.isHidden {
                 bestValueHeightConstraint.constant = 0