Add quickstart for Front Door (classic)

quickstart/101-front-door-classic/variables.tf

@@ -0,0 +1,17 @@
+variable "location" {
+  type    = string
+  default = "westus2"
+}
+
+variable "resource_group_name" {
+  type    = string
+  default = "FrontDoor"
+}
+
+variable "backend_address" {
+  type = string
+}
+
+resource "random_id" "front_door_name" {
+  byte_length = 8
+}