portico: Pass requested sponsorship context to plan page.

corporate/lib/stripe.py

@@ -2354,7 +2354,7 @@ class BillingSession(ABC):
             ):  # nocoverage
                 return sponsorship_request.requested_plan
 
-        # We only support sponsorships for these plans.
+        # Default name for sponsorship plan.
         sponsored_plan_name = CustomerPlan.name_from_tier(CustomerPlan.TIER_CLOUD_STANDARD)
         if is_remotely_hosted:
             sponsored_plan_name = CustomerPlan.name_from_tier(

corporate/views/portico.py

@@ -80,6 +80,7 @@ class PlansPageContext:
     customer_plan: Optional[CustomerPlan] = None
     is_legacy_server_with_scheduled_upgrade: bool = False
     legacy_server_new_plan: Optional[CustomerPlan] = None
+    requested_sponsorship_plan: Optional[str] = None
 
     billing_base_url: str = ""
 
@@ -140,6 +141,7 @@ def remote_realm_plans_page(
         free_trial_days=get_free_trial_days(True),
         billing_base_url=billing_session.billing_base_url,
         is_sponsored=billing_session.is_sponsored(),
+        requested_sponsorship_plan=billing_session.get_sponsorship_plan_name(customer, True),
     )
 
     context.on_free_tier = customer is None and not context.is_sponsored
@@ -192,6 +194,7 @@ def remote_server_plans_page(
         free_trial_days=get_free_trial_days(True),
         billing_base_url=billing_session.billing_base_url,
         is_sponsored=billing_session.is_sponsored(),
+        requested_sponsorship_plan=billing_session.get_sponsorship_plan_name(customer, True),
     )
 
     context.on_free_tier = customer is None and not context.is_sponsored