Replace lodash with built-ins where possible to reduce bundle size (#1766)

* add tslint rule to disallow lodash.isUndefined

* add tslint rule to disallow lodash.isNull

* apply fixes

packages/contracts-gen/package.json

@@ -9,6 +9,7 @@
     "types": "lib/src/index.d.ts",
     "scripts": {
         "lint": "tslint --format stylish --project .",
+        "fix": "tslint --fix --format stylish --project .",
         "clean": "shx rm -rf lib",
         "build": "tsc -b",
         "build:ci": "yarn build"