Make OSInAppMessagePrompt public

[jkasten2]

Description

One Line Summary

The public OSInAppMessageAction.getPrompts method which returns List<OSInAppMessagePrompt> so making OSInAppMessagePrompt public as well.

Details

Motivation

This change allows OSInAppMessageAction.getPrompts to be used by app developers. This change is also required to fix access errors from some tooling such as Xamarin Binding to this SDK's .aar file.

Testing

Manual testing

Tested with the OneSignal Xamarin Android Binding project (from the OneSignal/OneSignal-Xamarin-SDK 3.x.x) and run on an Android 12 emulator.

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
• 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.
• I have reviewed this PR myself, ensuring it meets each checklist item

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This change is 

[jkasten2]

Looks to be flaky unrelated test.

com.test.onesignal.OutcomeEventIntegrationTests > testCleaningCachedNotifications_after7Days_willAlsoCleanUniqueOutcomeNotifications FAILED
    junit.framework.AssertionFailedError: expected:<0> but was:<5>
        at junit.framework.Assert.fail(Assert.java:50)
        at junit.framework.Assert.failNotEquals(Assert.java:287)
        at junit.framework.Assert.assertEquals(Assert.java:67)
        at junit.framework.Assert.assertEquals(Assert.java:199)
        at junit.framework.Assert.assertEquals(Assert.java:205)
        at com.test.onesignal.OutcomeEventIntegrationTests.testCleaningCachedNotifications_after7Days_willAlsoCleanUniqueOutcomeNotifications(OutcomeEventIntegrationTests.java:1128)

re-running tests