Actor source generator does not copy generic constraints for type parameters

## Expected Behavior

Given the following actor interface:

```csharp
using Dapr.Actors.Generators;
using System.Threading.Tasks;

namespace Test
{
public interface ITrait
{
string GetName();
}

[GenerateActorClient]
public interface ITestActor where TTrait : ITrait
{
Task SetTrait(TTrait trait);
Task GetTrait(string name);
}
}
```

it should generate a class definition like this:

```csharp
public sealed class TestActorClient : Test.ITestActor where TTrait : Test.ITrait
...
```

## Actual Behavior

instead, it generates this:

```csharp
public sealed class TestActorClient : Test.ITestActor
...
```

The constraints are not copied.

## Steps to Reproduce the Problem

Use the DAPR source generator package with the above actor interface, then examine the analyzer output (or try to compile it.) It will fail.

## Release Note

RELEASE NOTE:

Start with the Dapr source generator package and reproduce the issue using the generic actor interface shown in the report. Inspect the analyzer output and compile the generated client; done means the generated class preserves the type parameter constraint and the example builds successfully.

Written by the indexing model from the issue text.