feat: [SDK-4774] add OneSignal project settings support

[fadi-george]

Description

One Line Summary

Adds a Project Settings page for OneSignal SDK configuration and cleans up Unity demo setup artifacts.

Details

Motivation

The location module opt-out is a persistent project-level SDK setting, so it should be discoverable from Unity's Project Settings instead of only through a menu-bar toggle. This PR also keeps the demo projects reproducible after running SDK setup by checking in generated demo assets and adding cleanup scripts.

Scope

Adds Project Settings > OneSignal for the Disable Location Module setting and removes the old OneSignal > Disable Location Module menu item so Project Settings is the single interactive UI path. Updates Unity demo setup files, generated EDM4U/Android plugin assets for demo-no-location, adds demo cleanup scripts, bumps package Unity metadata to the supported 2021.3 minimum, and replaces obsolete iOS GetApplicationIdentifier(BuildTargetGroup.iOS) calls with NamedBuildTarget.iOS.

Testing

Unit testing

No unit tests were added; these changes are Unity Editor UI, demo setup, package metadata, and generated demo asset updates.

Manual testing

Tested the following Unity demo build paths:

• Built examples/demo via Unity Editor for iOS and Android.
• Built examples/demo-no-location via Unity Editor for iOS and Android.
• Built examples/demo via build scripts: run-android.sh and run-ios.sh.
• Built examples/demo-no-location via build scripts: run-android.sh and run-ios.sh.

Also verified the location opt-out is configured from Project Settings > OneSignal after removing the menu-bar toggle. Remaining Unity Editor Analytics deprecation warnings in VSAttribution.cs are pre-existing and intentionally left unchanged.

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
  • Demo setup cleanup and Project Settings support are grouped around making the Unity location opt-out setup easier to use and reproduce.
• Any Public API changes are explained in the PR details and conform to existing APIs
  • No runtime public API changes.

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
  • Automated tests were not rerun for this cleanup PR; manual Unity Editor and script validation covered the changed setup flows.
• I have personally tested this on my device, or explained why that is not possible
  • Manual validation was performed through Unity Editor and script demo builds as described above.

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.