Add package.json RubyGems Bundler install scripts

- vanilla
- frozen
  - prevent lockfile updates
  - require existing lockfile
- ignore deprecation warning
  - `bundle config set --local <flag> 'true'` too verbose for a script

Author: leotm

package.json

@@ -10,6 +10,8 @@
     "watchman:reset": "watchman watch-del-all && watchman shutdown-server",
     "android": "react-native run-android --active-arch-only",
     "android:release": "react-native run-android --active-arch-only --mode release",
+    "gems": "bundle install",
+    "gems:frozen": "bundle install --frozen",
     "ios": "react-native run-ios",
     "ios:release": "react-native run-ios --mode Release",
     "ios:light": "xcrun simctl ui booted appearance light",