Chore: fix Xcode project navigator files reference

[nan-li]

Description

One Line Summary

Clean up file references in Xcode workspace to make it easier to maintain, add, and remove files.

Details

Motivation

For example, most of the files within OneSignalLiveActivities directory are under a sub directory called Source. However, you could not see this in the project navigator. It becomes confusing when you add/remove files via the project navigator as they do not go where you think they should. Also did this for UnitTests and OneSignalLiveActivitiesFramework.

Real Folder Structure

Xcode project navigator BEFORE

Xcode project navigator AFTER

Scope

Clean up Xcode files structure so every file and folder in the project navigator matches the actual file/folder structure. Make all files that are a "reference" be the "real" file.

Testing

Manual testing

Builds and runs on iphone 13, iOS 18.6.2

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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