feat: Support UserIdentificationType in AppsFlyer Kit

[nickolas-dimitrakas]

Background

• Duplicates changes from the standalone AppsFlyer kit repo into the monorepo (appsflyer-6).
• Source PR: feat: Support UserIdentificationType mparticle-integrations/mparticle-apple-integration-appsflyer#54

What Has Changed

• Add userIdentificationType config so AppsFlyer's customer user ID can follow MPID, CustomerId, or legacy behavior
• Sync AppsFlyer customer user ID on identity callbacks (onIdentifyComplete, onLoginComplete, onLogoutComplete, onModifyComplete)
• setUserIdentity in MPID mode ignores customer-ID identity for AppsFlyer's customer user ID but still returns success
• Commerce and event routing resolve af_customer_user_id via customerIDForAppsFlyer:
• Mock now records writes to AppsFlyer's customerUserID property for test assertions
• New tests cover setUserIdentity for legacy, CustomerId, and MPID modes plus email and unsupported identity types

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Reference Issue (For employees only. Ignore if you are an outside contributor)

• NO JIRA

[cursor]

PR Summary

Medium Risk
Changes how the kit selects and syncs AppsFlyer customerUserID (MPID vs CustomerId) and updates it on identity callbacks, which can affect attribution/user linking. Scope is contained to the AppsFlyer kit and covered by new unit tests.

Overview
Adds a new userIdentificationType configuration to control whether AppsFlyer customerUserID follows the mParticle MPID, the mParticle CustomerId, or legacy behavior.

The kit now syncs customerUserID at init and on identity lifecycle callbacks (onIdentifyComplete, onLoginComplete, onLogoutComplete, onModifyComplete), and ensures commerce/events attach af_customer_user_id using the configured identifier. Tests were expanded with a mock that tracks customerUserID writes and new cases covering MPID/CustomerId/legacy modes and unsupported identities.

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[github-actions]

📦 SDK Size Impact Report

Measures how much the SDK adds to an app's size (with-SDK minus without-SDK).

Metric	Target Branch	This PR	Change
App Bundle Impact	1.66 MB	1.66 MB	+N/A
Executable Impact	896 bytes	896 bytes	+N/A
XCFramework Size	5.47 MB	5.47 MB	+N/A

➡️ SDK size impact change is minimal.

Raw measurements

Target branch (workstation/9.0-Release):

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1788,"with_sdk_executable_size_bytes":76360,"sdk_impact_kb":1704,"sdk_executable_impact_bytes":896,"xcframework_size_kb":5604}

This PR:

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1788,"with_sdk_executable_size_bytes":76360,"sdk_impact_kb":1704,"sdk_executable_impact_bytes":896,"xcframework_size_kb":5604}

[denischilik]

Few changes, the rest looks good

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[denischilik]

LGTM