fix(data): Gen2 hasOne associatedFields compile issue

[lawmicha]

Issue #

#3699 #3735

Description

This PR allows has-one to reference multiple CodingKey's of the associated model by having an associatedFieldNames, which is the extension of the single value associatedFieldName. This was a change added in Gen2's code generation logic.

The related documentation for testing can be found starting at https://docs.amplify.aws/swift/build-a-backend/data/data-modeling/relationships/#model-a-one-to-one-relationship

The tests for this documentation can be found in GraphQLCartCustomer4Tests

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
  https://github.com/aws-amplify/amplify-swift/actions/runs/9951987862
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

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

[codecov]

Codecov Report

Attention: Patch coverage is 52.63158% with 9 lines in your changes missing coverage. Please review.

Project coverage is 68.49%. Comparing base (151cac6) to head (2cb4714).
Report is 2 commits behind head on main.

Files	Patch %	Lines
...Model/Internal/Schema/ModelSchema+Definition.swift	0.00%	8 Missing ⚠️
...ources/AWSAPIPlugin/Core/AppSyncListProvider.swift	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3700      +/-   ##
==========================================
- Coverage   68.54%   68.49%   -0.05%     
==========================================
  Files        1079     1079              
  Lines       37580    37591      +11     
==========================================
- Hits        25758    25749       -9     
- Misses      11822    11842      +20     

Flag	Coverage Δ
API_plugin_unit_test	68.83% <0.00%> (ø)
AWSPluginsCore	68.56% <100.00%> (ø)
Amplify	47.56% <42.85%> (-0.11%)	⬇️
Analytics_plugin_unit_test	84.52% <ø> (ø)
Auth_plugin_unit_test	79.72% <ø> (+<0.01%)	⬆️
DataStore_plugin_unit_test	81.17% <100.00%> (-0.12%)	⬇️
Geo_plugin_unit_test	72.00% <ø> (ø)
Logging_plugin_unit_test	62.95% <ø> (ø)
Predictions_plugin_unit_test	37.32% <ø> (ø)
PushNotifications_plugin_unit_test	86.21% <ø> (ø)
Storage_plugin_unit_test	76.75% <ø> (ø)
unit_tests	68.49% <52.63%> (-0.05%)	⬇️

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