Unimplemented Tests: WorkloadSetInstallationRecordIsWrittenCorrectly and TurnOffWorkloadSetUpdateMode

### Describe the bug
The tests `WorkloadSetInstallationRecordIsWrittenCorrectly` and `TurnOffWorkloadSetUpdateMode` are currently marked as "Not Implemented" and throw `NotImplementedException`.

The relevant code snippet is:
```csharp
[Fact(Skip = "https://github.com/dotnet/sdk/issues/46905")]
public void WorkloadSetInstallationRecordIsWrittenCorrectly()
{
// Should the workload set version or the package version be used in the registry?
throw new NotImplementedException();
}

[Fact(Skip = "https://github.com/dotnet/sdk/issues/46905")]
public void TurnOffWorkloadSetUpdateMode()
{
// If you have a workload set installed and then turn off workload set update mode, what should happen?
// - Update should update individual manifests
// - Resolver should ignore workload sets that are installed
throw new NotImplementedException();
}
```

### Expected behavior
These tests should be implemented to verify the following behaviors:
1. **WorkloadSetInstallationRecordIsWrittenCorrectly**:
- Ensure that the workload set version or the package version is correctly recorded during installation.

2. **TurnOffWorkloadSetUpdateMode**:
- Verify the behavior when the workload set update mode is turned off:
- Updates should update individual manifests.
- The resolver should ignore installed workload sets.