1. 1. Fix change stream cursor handling and consolidate log codes

This change improves the robustness of change stream operations by addressing several cursor management issues:

• Clear conflicting resume options (`startAtOperationTime`, `startAfter`) before setting `resumeAfter` to match server-side behavior
• Preserve `aggregateOptions` when storing cursor information and merge them properly during cursor recreation
• Update cursor objects in-place to maintain reference chains, ensuring callers always have the latest cursor ID
• Add debug logging for open cursor tracking to improve observability
• Consolidate V2 targeter log codes into a centralized `V2TargeterLogCodes` object and update all test files to use the shared constants

These fixes ensure change streams handle resume tokens correctly and maintain proper cursor state throughout their lifecycle.