[AI-FSSDK] [FSSDK-12670] Block ODP identify event for single identifier

[jaeopt]

Summary

Fixes ODP identify event to only send when multiple valid identifiers exist. Previously, the SDK could send an identify event with just a single VUID when userId was nil, which provides no identity-linking value.

Changes

• Added identifier count guard in OdpEventManager.identifyUser to skip event dispatch when fewer than 2 valid identifiers are present
• Added empty string check for both vuid and userId before adding to identifiers map
• Added debug-level logging when the identify event is skipped due to single identifier
• Updated test for nil userId case to expect no event queued (single identifier is now skipped)

Jira Ticket

FSSDK-12670

Notes

• Reference implementation: Python SDK PR [FSSDK-9419]: feat: Swift async-await support added #513
• The count check is placed in OdpEventManager (where identifiers map is constructed) rather than OdpManager (which routes based on VUID detection)

[coveralls]

Coverage is 93.828% — ai/jaeopt/FSSDK-12670-odp-event into master. No base build found for master.