add template for directives

fuzz/corpus/hashicorp%terraforminternal%terraform%testdata%vars-basic-bool%main.tf

@@ -0,0 +1,10 @@
+// At the time of writing Terraform doesn't formally support a boolean
+// type, but historically this has magically worked. Lots of TF code
+// relies on this so we test it now.
+variable "a" {
+    default = true
+}
+
+variable "b" {
+    default = false
+}