Restore parameterless Player constructor for testability

[DevD4v3]

Previous versions exposed a protected parameterless constructor:

protected Player()
{
}

This allowed creating lightweight test doubles by deriving from Player and overriding virtual members such as Name, Team, Health, etc.

The current constructor requires IOmpEntityProvider and IPlayer instances:

protected Player(IOmpEntityProvider entityProvider, IPlayer player)

which makes it difficult to create fake Player implementations for unit tests without depending on runtime infrastructure.

Would it be possible to restore the parameterless constructor for testing scenarios?

[ikkentim]

I've added some changes in #596 where the open.mp component no longer get cast when the value is null.

After that, a mock library like Moq can mock these types now:

public class Example
{
    [Fact]
    public void MockTest()
    {
        var mock = new Mock<Player>(null!, default(IPlayer)); // Provide values for the Player ctor. All null/default values should suffice.

        mock.SetupProperty(x => x.Name, "John");

        Player player = mock.Object;

        player.Name.ShouldBe("John");
    }
}

It would be nice if we could avoid having to provide null values for the Mock, but adding parameterless constructors will be more of a mess.

[DevD4v3]

It works well!