Fix property lookup to support inheritance in pagination response models

[Copilot]

The emitter failed when pagination properties (@nextLink, @pageItems) were defined in base models rather than directly on the response model. Property lookups used Properties.First() which only searched direct properties, causing InvalidOperationException for inherited properties.

Changes

• Added recursive property lookup: New FindPropertyInModelHierarchy() method traverses the model inheritance chain to locate properties defined in base classes
• Updated CollectionResultDefinition.GetNextPagePropertyType(): Replaced direct property access with hierarchy-aware lookup
• Updated ModelProviderSnippets.BuildPropertyAccessExpression(): Applied same pattern for consistency across property access paths
• Added test coverage: 4 test cases covering sync/async and generic/non-generic scenarios with inherited pagination properties

Example

Now supports this pattern:

model ResponseList {
  @nextLink
  nextLink?: string;
}

model FooResponseList extends ResponseList {
  @pageItems
  value?: FooResource[];
}

Previously, the emitter would throw when trying to locate nextLink on FooResponseList since it only checked direct properties.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[http-client-csharp] failed to find nested nextLink property for a list operation</issue_title>
<issue_description>If the response model is inherited from another model that only defines nextLink, like this:

model ResponseList {
  /**
   * The uri to fetch the next page of resources. Call ListNext() fetches next page of resources.
   */
  @nextLink
  nextLink?: string;
}

model FooResponseList extends ResponseList {
  /**
   * List of resources.
   */
  @pageItems
  value?: FooResource[];
}

Then the emitter throws an exception because it doesn’t check for nested nextLink values. This results in an error like the following:

      Sequence contains no matching element
         at System.Linq.ThrowHelper.ThrowNoMatchException()
         at System.Linq.Enumerable.First[TSource](IEnumerable`1 source, Func`2 predicate)
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.CollectionResultDefinition.GetNextPagePropertyType()
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.CollectionResultDefinition..ctor(ClientProvider client, InputPagingServiceMethod serviceMethod, CSharpType itemModelType, Boolean isAsync)
         at Azure.Generator.Providers.AzureCollectionResultDefinition..ctor(ClientProvider client, InputPagingServiceMethod serviceMethod, CSharpType itemModelType, Boolean isAsync)
         at Azure.Generator.Providers.AzureClientResponseProvider.CreateClientCollectionResultDefinition(ClientProvider client, InputPagingServiceMethod serviceMethod, CSharpType type, Boolean isAsync)
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ScmMethodProviderCollection.BuildProtocolMethod(MethodProvider createRequestMethod, Boolean isAsync, Boolean shouldMakeParametersRequired)
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ScmMethodProviderCollection.BuildMethods()
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ScmMethodProviderCollection.get_MethodProviders()
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ScmMethodProviderCollection.GetEnumerator()
         at System.Collections.Generic.List`1.AddRange(IEnumerable`1 collection)
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ClientProvider.BuildMethods()
         at Microsoft.TypeSpec.Generator.Providers.TypeProvider.get_Methods()
         at Microsoft.TypeSpec.Generator.ClientModel.Providers.ClientProvider.GetMethodCollectionByOperation(InputOperation operation)
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes [http-client-csharp] failed to find nested nextLink property for a list operation #9418

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