Run block variable references (#1129)

Signed-off-by: Christian Mesh <christianmesh1@gmail.com>

internal/command/testdata/test/variables_reference/main.tftest.hcl

@@ -0,0 +1,15 @@
+variables {
+  content = "some value"
+}
+
+run "setup" {
+  module {
+    source = "./setup"
+  }
+}
+
+run "test" {
+  variables {
+    file_name = run.setup.file_name
+  }
+}

internal/command/testdata/test/variables_reference/setup/main.tf

@@ -0,0 +1,7 @@
+variable "content" {
+  type = string
+}
+
+output "file_name" {
+  value = "output_value"
+}