fix(gulp-util): add chalk as a dependency (#20976)

As of `chalk@2.2.0` (https://github.com/chalk/chalk/releases/tag/v2.2.0)
the project is providing it's own type definitions. See the specific
commit below for more details.

f653b061d6

types/gulp-util/package.json

@@ -0,0 +1,6 @@
+{
+    "private": true,
+    "dependencies": {
+        "chalk": "^2.2.0"
+    }
+}