feat(core): impl billing settings (#4652)

packages/backend/server/src/schema.gql

@@ -112,6 +112,7 @@ type UserInvoice {
   status: InvoiceStatus!
   reason: String!
   lastPaymentError: String
+  link: String
   createdAt: DateTime!
   updatedAt: DateTime!
 }
@@ -278,6 +279,9 @@ type Mutation {
 
   """Create a subscription checkout link of stripe"""
   checkout(recurring: SubscriptionRecurring!): String!
+
+  """Create a stripe customer portal to manage payment methods"""
+  createCustomerPortal: String!
   cancelSubscription: UserSubscription!
   resumeSubscription: UserSubscription!
   updateSubscriptionRecurring(recurring: SubscriptionRecurring!): UserSubscription!