Codegen for openapi v1641.

Changelog

• Change CustomerSession.CreateParams.customer, InvoiceItem.CreateParams.customer, PaymentMethod.AttachParams.customer, Subscription.CreateParams.customer, billing.CreditBalanceSummary.RetrieveParams.customer, billing.CreditBalanceTransaction.ListParams.customer, billing.CreditGrant.CreateParams.customer, and billingportal.Session.CreateParams.customer to be optional
• Add support for update_line_items on CheckoutSession.Permission and checkout.Session.CreateParamsPermission
• Change type of Invoice.Parent.SubscriptionDetail.PauseCollection.behavior and QuotePreviewInvoice.Parent.SubscriptionDetail.PauseCollection.behavior from string to enum('keep_as_draft'|'mark_uncollectible'|'void')
• Change type of QuotePreviewInvoice.Parent.SubscriptionDetail.subscription from string to expandable($Subscription)
• Add support for id and text on TerminalReader.Action.CollectInput.Input.Selection.Choice, TerminalReader.Action.CollectInput.Input.Selection, and terminal.Reader.CollectInputsParamsInputSelectionChoice
• Remove support for value on TerminalReader.Action.CollectInput.Input.Selection.Choice, TerminalReader.Action.CollectInput.Input.Selection, and terminal.Reader.CollectInputsParamsInputSelectionChoice