Offer an "Implement with Mixin" code action when adding an interface to a type

[pgenfer]

Remark: Issue #11 was split into two parts for easier administration. This is the second part.

Say I have the following mixin

public class NameMixin: INamed
{
    public string Name { get; set; }
}

and INamed is defined as follows

public interface INamed
{
    string Name { get; set; } = string.Empty;
}

it would be very convenient to offer an Implement with NamedMixin code action when adding the INamed interface to a type not having an implementation.

Thanks to @aluanhaddad for suggesting this feature.

[aluanhaddad]

Thanks for implementing this. I love the feature!

[pgenfer]

Implemented in V1.4