add template for directives

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

@@ -0,0 +1,14 @@
+variable "a" {
+  default = "foo"
+  type    = string
+}
+
+variable "b" {
+  default = []
+  type    = list(string)
+}
+
+variable "c" {
+  default = {}
+  type    = map(string)
+}