breaking(pod): remove unused API & bump minimum version requirements to 1.8.0

[erisu]

Motivation, Context, & Description

Improve cocoapods support by increasing the minimum required version and removing unused logic.

• Increase minimum supported version starting at 1.8.0
  • Since 1.8.0, CDN is enabled by default and is highly recommended as it no longer requires to checkout and sync the cocoapods repo. This greatly improves the speed.

Testing

• npm t

Checklist

• [x] I've run the tests to see all new and existing tests pass

[AdamLak]

Too much refactor: https://github.com/apache/cordova-ios/pull/1018