fix: $ref structure preservation during intermediate progress updates

[naxty]

Summary

• Add early return in updateResourceUpdateFromProgress to skip property updates when progress hasn't finished successfully
• Add comprehensive test for the intermediate progress self-cannibalization bug

Problem

During create operations with long-running cloud resources, the plugin returns intermediate progress updates with OperationStatusInProgress and empty properties {}. When these empty properties were merged with user properties, arrays containing $ref structures (used for dependency tracking) were being wiped out.

The self-cannibalization bug:

1. User creates a resource with properties containing $ref structures in arrays (e.g., disks[].source.$ref, networkInterfaces[].network.$ref)
2. First progress update arrives with InProgress status and empty properties {}
3. Merge logic uses plugin properties as base, wiping out user's arrays
4. Second progress update arrives with Success status and full properties
5. But the $ref structures are already lost - they can never be recovered

Solution

Skip property updates entirely when the progress hasn't finished successfully. The fix adds an early return in resource update.

// Only update properties when the operation has finished successfully.
// Intermediate progress updates may have empty/partial properties which would
// wipe out $ref structures needed for dependency tracking.
if !progress.FinishedSuccessfully() {
    return nil
}

This ensures that:

• State, NativeID, and timestamps are still updated during intermediate progress
• Properties are only merged when the operation completes with OperationStatusSuccess
• $ref structures survive the entire create/update lifecycle

Test scenario:

1. Create ResourceUpdate with properties containing disks and networkInterfaces arrays with $ref structures
2. Record intermediate progress (InProgress status) with empty properties {}
3. Verify arrays and $ref structures are still intact
4. Record final progress (Success status) with full properties including $ref objects
5. Verify $ref structures are preserved and $value fields are correctly populated