3.0.0 Beta2

Major Release 3.0.0 Beta2🛠️

⚠️ This is a major beta release that contains breaking API changes.
See the full list of changes along with step-by-step guides to upgrade.
https://documentation.onesignal.com/docs/mobile-2020-api-migration-guide

❓ Please provide feedback and bug reports with the beta version included in the title to this repo's issue tracker.
https://github.com/OneSignal/OneSignal-Cordova-SDK/issues

Some highlights for this release

• Typescript support added #704