Allow webapp to request legacy cloud products. (#18528)

* Change internal getProducts to filter on a set of families instead of a single family.
* Extend /products endpoint to be able to return any of the current four sets of product families.
* Use include_legacy query param to decide which cloud products to request.

einterfaces/cloud.go

@@ -8,7 +8,7 @@ import (
 )
 
 type CloudInterface interface {
-	GetCloudProducts(userID string) ([]*model.Product, error)
+	GetCloudProducts(userID string, includeLegacyProducts bool) ([]*model.Product, error)
 
 	CreateCustomerPayment(userID string) (*model.StripeSetupIntent, error)
 	ConfirmCustomerPayment(userID string, confirmRequest *model.ConfirmPaymentMethodRequest) error