Update es2017 to es2019

As @retyui pointed out our new minimal iOS version for RN 0.69 is 12.4
- react-native-community/react-native-template-typescript#275
  - facebook/react-native@982ca30

We've updated our template too now
- react-native-community/react-native-template-typescript#276

I bumped our Hermes podspec earlier as well
- facebook/react-native#33939
  - facebook/react-native@f56d701

Unless there's reason to keep our recommended TSConfig base pre-0.69

bases/react-native.json

@@ -7,7 +7,7 @@
     "module": "commonjs",
     "types": ["react-native", "jest"],
     "lib": [
-      "es2017"
+      "es2019"
     ],
     "allowJs": true,
     "jsx": "react-native",