[BUG] Constructor detection on deserialization only works when all ctor arguments are of simple type

[lbnascimento]

Version
LiteDB v5.0.8, .NET Core 3.1

Describe the bug
Constructor detection on deserialization only works when all the arguments in the ctor are of a simple type (more specifically, of a type present in the Reflection.ConvertType dictionary).

In the example below, if the DateTimeOffset parameter is removed, the code works as expected.

Code to Reproduce

[Fact]
public void Custom_Ctor_Non_Simple_Types()
{
    var doc = new BsonDocument { ["_id"] = 1, ["Name"] = "myName", ["DateTimeOffset"] = new DateTime(2020, 01, 01).ToUniversalTime() };
    var obj = _mapper.ToObject<MyClass>(doc);

    obj.Id.Should().Be(1);
    obj.Name.Should().Be("myName");
    obj.DateTimeOffset.Should().Be(new DateTimeOffset(new DateTime(2020, 01, 01)));
}

Expected behavior
Deserialization with custom ctor working for any parameter type.

Additional context
This is very important for compatibility with C# 9 positional records.