Generate source for RelayCommandAttribute on record as well

### Overview

Records should also be able to generate `RelayCommand` just like classes do.

### API breakdown

No new API

### Usage example

Data layer has a record:
```cs
public record DataRecord(int Stuff, IListListOfStuff);
```

In the MVVM layer we want to provide commands to add or remove from the ListOfStuff:

```cs
public partial record DataRecordVM(DataRecord dr) : DataRecord(dr.Stuff, dr.ListOfStuff)
{
}
```

Inside `DataRecordVM` I'd like to add to the list
```cs
[RelayCommand]
private void Add(int newStuff) => ListOfStuff.Add(newStuff);
```

### Breaking change?

No

### Alternatives

The alternative is to instantiate `RelayCommand` by hand.

The other alternative is to use a class which has the record as its member, but it is too verbose:
```cs
public partial class DataClassVM(DataRecord dr)
{
[RelayCommand]
private void Add(int newStuff) => dr.ListOfStuff.Add(newStuff);

// expose if necessary
public IList DataRecord => dr.ListOfStuff;
public int Stuff => dr.Stuff;
}
```

### Additional context

_No response_

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