Add support to a public access to cloudsql-instance (#754)

* feat: add support to a public access to cloudsql-instance

* doc: update cloudsql-instance doc changing the ipv4_enabled parameter description

* test: fix assertion test to ipv4_enabled

tests/modules/cloudsql_instance/fixture/main.tf

@@ -34,4 +34,5 @@ module "test" {
   users                = var.users
   tier                 = var.tier
   deletion_protection  = var.deletion_protection
+  ipv4_enabled         = var.ipv4_enabled
 }

tests/modules/cloudsql_instance/fixture/variables.tf

@@ -112,3 +112,8 @@ variable "deletion_protection" {
   type    = bool
   default = false
 }
+
+variable "ipv4_enabled" {
+  type    = bool
+  default = false
+}