export OneSignalPlugin so it can be imported in consumer typescript code

[wilgert]

Description

This exports the OneSignalPlugin class so it can be used in TypeScript.

Details

Motivation

In the 3.0.x versions of this plugin we could do import { OneSignalPlugin } from 'onesignal-cordova-plugin'; to get strong typing while dependency injecting the oneSignal plugin in our Angular code. With version 3.1.0 this stopped working. To fix it a export keyword was added.

Manual testing

Tested the app was building again after adding this keyword.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
  • If it is hard to explain how any codes changes are related to each other then it most likely needs to be more than one PR
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
  • Simplify with less code, followed by splitting up code into well named functions and variables, followed by adding comments to the code.
• I have reviewed this PR myself, ensuring it meets each checklist item
  • WIP (Work In Progress) is ok, but explain what is still in progress and what you would like feedback on. Start the PR title with "WIP" to indicate this.

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This change is 

[nan-li]

Thanks for catching this and submitting this PR.

[nunoarruda]

Just for your curiosity, this looks like a matter of default export vs named export.

I've been using this plugin on a TypeScript project for a long time and since it was using a default export I had to import it like import OneSignal from 'onesignal-cordova-plugin' and I had strong typing and everything.

In sum...

Using default export:
Exporting: export default OneSignal
Importing: import OneSignal from 'onesignal-cordova-plugin' (you can rename OneSignal to whatever you like)

Using a named export:
Exporting: export class OneSignalPlugin
Importing: import { OneSignalPlugin } from 'onesignal-cordova-plugin' (you have to import it exactly as OneSignalPlugin and can only renamed it using an alias like import { OneSignalPlugin as OS } for example)

[ssisniega]

Hello boys!
I am using version 3.3.0 of the plugin.
I am getting this error: I cannot reference an instance method (in my example this.notificacionRecibida(...) ) in the delegate that receives the open push information.
How do you suggest I can fix it? If I inject the plugin dependency I get an error.

Thanks!