feat: add custom events support

[fadi-george]

Description

One Line Summary

• add custom events support for the cordova sdk

Cordova ios custom events

Cordova android custom events

Example app:

Details

• updates ios dependency (to 5.4.0) and android dep. (to 5.6.1)
• updates example file to test the new trackEvent method with complex properties
• updates OneSignalController.java & OneSignalPush.java to expose new android sdk trackEvent method. Adds Map helper functions to deal with complex object properties
• updates OneSignalPush.m (& header) to expose new track ios sdk trackEvent method
• updates main UserNamespace.ts file to have new trackEvent method to call respective platform's trackEvent function

Motivation

Want to allow usage for custom events method to more sdks / developers.

Testing

• You can run the example file and check the dashboard custom events logs
• For android run: ionic capacitor run android
• For ios run: ionic capacitor run ios

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.

---

This change is 

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[nan-li]

LGTM thx!