Add package.json CocoaPods install scripts

- vanilla
- frozen (for CI, fail if Podfile or lockfile changes)
- clean
  - remove Pods folder and lockfile
  - update all spec-repos in local user OS .cocoapods\repos dir
  - avoid --clean-install (incremental_installation only)
- use proj CocoaPods, avoid global system version
  - ideally installed via homebrew avoiding sudo-wide changes

Author: leotm

package.json

@@ -12,6 +12,9 @@
     "android:release": "react-native run-android --active-arch-only --mode release",
     "gems": "bundle install",
     "gems:frozen": "bundle install --deployment",
+    "pods": "cd ios && bundle exec pod install",
+    "pods:frozen": "cd ios && bundle exec pod install --deployment",
+    "pods:clean": "cd ios && rm -rf Pods Podfile.lock && bundle exec pod install --repo-update",
     "ios": "react-native run-ios",
     "ios:release": "react-native run-ios --mode Release",
     "ios:light": "xcrun simctl ui booted appearance light",