Apply JSON schema to task.json files in VS Code (#421)

Utility for developers working on this project: apply Microsoft's Azure Pipelines Tasks JSON schema to all of our `task.json` files.

Author: bryceitoc9

.vscode/settings.json

@@ -9,5 +9,11 @@
         "build": true,
         "package": true,
         ".vscode": true
-    }
+    },
+    "json.schemas": [
+        {
+            "fileMatch": ["/task.json"],
+            "url": "https://raw.githubusercontent.com/Microsoft/azure-pipelines-task-lib/master/tasks.schema.json"
+        }
+    ]
 }