Add support for Starlark.

Support is similar to Python, as it is a python dialect.  However, it does not support block comments.

See spec: https://github.com/bazelbuild/starlark/blob/master/spec.md

syntax.json

@@ -188,6 +188,15 @@
       }
     ]
   },
+  {
+    "language": "Starlark",
+    "markers": [
+      {
+        "type": "line",
+        "pattern": "#"
+      }
+    ]
+  },
   {
     "language": "TypeScript",
     "markers": [