Add yaml parsing package

Author: jcreedcmu

extensions/ql-vscode/package.json

@@ -341,6 +341,7 @@
     "classnames": "~2.2.6",
     "fs-extra": "^8.1.0",
     "glob-promise": "^3.4.0",
+    "js-yaml": "^3.12.0",
     "node-fetch": "~2.6.0",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
@@ -359,6 +360,7 @@
     "@types/glob": "^7.1.1",
     "@types/google-protobuf": "^3.2.7",
     "@types/gulp": "^4.0.6",
+    "@types/js-yaml": "~3.12.1",
     "@types/jszip": "~3.1.6",
     "@types/mocha": "~5.2.7",
     "@types/node": "^12.0.8",