hcl: Added basic hcl frontend

examples/graph0.hcl

@@ -0,0 +1,20 @@
+resource "file" "file1" {
+  path = "/tmp/mgmt-hello-world"
+  content = "hello, world"
+  state = "exists"
+}
+
+resource "noop" "noop1" {
+  test = "nil"
+}
+
+edge "e1" {
+  from = {
+    kind = "noop"
+    name = "noop1"
+  }
+  to = {
+    kind = "file"
+    name = "file1"
+  }
+}

examples/graph1.hcl

@@ -0,0 +1,4 @@
+resource "exec" "exec1" {
+  cmd = "cat /tmp/mgmt-hello-world"
+  state =  "present"
+}