Add test to ensure the scope is set correctly on an existing resource's role assignments bicep.

[eerhardt]

No description provided.

[Copilot]

Pull Request Overview

This PR adds a test to ensure that the correct scope is set on an existing resource's role assignments in the Bicep output.

• The test now builds a service provider and retrieves the DistributedApplicationModel from DI.
• It adds extra assertions for verifying the manifest and Bicep output for the messaging roles resource.

Comments suppressed due to low confidence (2)

tests/Aspire.Hosting.Azure.Tests/ExistingAzureResourceTests.cs:219

• [nitpick] Consider renaming 'messagingRoles' to a more descriptive name like 'messagingRolesResource' to better reflect its purpose.

var messagingRoles = Assert.Single(model.Resources.OfType<AzureProvisioningResource>().Where(r => r.Name == $"messaging-roles"));

tests/Aspire.Hosting.Azure.Tests/ExistingAzureResourceTests.cs:238

• [nitpick] Comparing multi-line string literals can be brittle due to minor whitespace variations; consider normalizing whitespace or using a more flexible comparison method.

expectedBicep = """ ...