[Bug Report] DPS query API does not populate enrollment assignment information

# Context

- **OS, version, SKU and CPU architecture used:** Windows 10 Desktop x64, Azure App Service (Linux based)
- **Application's .NET Target Framework :** net8.0
- **SDK version used:** Microsoft.Azure.Devices.Provisioning.Service 1.18.4

## Description of the issue
The DPS SDK contains wrapper methods around two DPS APIs:
(a) query all enrollments for a DPS instance
(b) get a single enrollment from the DPS instance

Method (b) works correctly, but when using version (a), the enrollment objects are all missing the `RegistrationState` information. This causes us to have to retrieve each individual enrollment rather than querying the list once and using the information as-is.

## Code sample exhibiting the issue
```
ProvisioningServiceClient provisioningServiceClient =
ProvisioningServiceClient.CreateFromConnectionString("");

IndividualEnrollment goodResult = await provisioningServiceClient.GetIndividualEnrollmentAsync("");
// here, goodResult.RegistrationState is a valid object containing IoT Hub assignment details

Query query = provisioningServiceClient.CreateIndividualEnrollmentQuery(new QuerySpecification(string.Empty));
while(query.HasNext())
{
QueryResult result = await query.NextAsync();
IReadOnlyList badResults = result.Items.OfType()
.Select(enrollment => enrollment.RegistrationState).ToList();
// here, every item in badResults will be null
}
```

Start with CreateIndividualEnrollmentQuery and QueryResult mapping, then compare the behavior with GetIndividualEnrollmentAsync using the supplied reproduction. Confirm whether query results populate IndividualEnrollment.RegistrationState; done means each returned enrollment includes the assignment information that the individual lookup provides.

Written by the indexing model from the issue text.