fix(aws-cdk): cdk migrate deduplication drops resources with compound identifiers

[Adityaj0]

Reason for this change

cdk migrate --from-scan can silently drop real, distinct resources from the generated CDK app/template. deduplicateResources() in packages/aws-cdk/lib/commands/migrate.ts computed its uniqueness key using only the first key of a resource's ResourceIdentifier map:

const key = Object.keys(resource.ResourceIdentifier!)[0];
const uniqueIdentifer = `${resource.ResourceType}:${key}:${resource.ResourceIdentifier![key]}`;

Some CloudFormation resource types have compound identifiers with more than one key (e.g. AWS::Route53::KeySigningKey is identified by the pair HostedZoneId + Name, as already documented elsewhere in this codebase in packages/@aws-cdk/toolkit-lib/lib/api/resource-import/importer.ts). Two distinct resources that merely share the value of their first identifier key collided on the same dedup key and one silently overwrote the other, with no warning to the user.

Description of changes

Changed deduplicateResources() to build its uniqueness key from the full, sorted set of ResourceIdentifier entries instead of just the first one, so resources are only considered duplicates when their entire identifier matches.

Description of how you validated changes

Added a regression test in packages/aws-cdk/test/commands/migrate.test.ts that scans two resources of type AWS::Route53::KeySigningKey sharing the same HostedZoneId but different Name values, and asserts both are still sent to CreateGeneratedTemplateCommand. Verified the test fails against the pre-fix code (both resources collapse into one) and passes after the fix. Ran the full migrate.test.ts suite — all tests pass.

Checklist

• Unit tests added/updated
• Integration tests added/updated (if deploying new resource types or cross-service interactions) - not needed, this is pure logic
• No manual edits to generated files

---

Closes #1878

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.31%. Comparing base (7ff50e7) to head (aeccd94).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1879      +/-   ##
==========================================
+ Coverage   91.10%   91.31%   +0.21%     
==========================================
  Files          80       80              
  Lines       12205    12207       +2     
  Branches     1742     1750       +8     
==========================================
+ Hits        11119    11147      +28     
+ Misses       1050     1024      -26     
  Partials       36       36              

Flag	Coverage Δ
suite.unit	91.31% <100.00%> (+0.21%)	⬆️

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