closes #161 Auto-Evaluation of the Status property when Errors ou ValidationErrors are added to the result.

[Ewerton]

Auto-evaluate the Status property when Errors ou ValidationErrors are added to the result.
It only works when the result is created as Ok(), Error() ou Invalid().

The following unit test describes the functioning of this PR

 [Fact]
 public void ErrorAndValidationErrorChanged()
 {
     Result result = Result.Success(); // Created as Ok
     result.IsSuccess.Should().Be(true);
     result.Status.Should().Be(ResultStatus.Ok);

     // Adding a validation error
     result.ValidationErrors.Add(new ValidationError("Validation Error 1"));
     result.IsSuccess.Should().Be(false);
     result.Status.Should().Be(ResultStatus.Invalid); // <- Status changed to Invalid

     // Adding an Error
     result.Errors.Add("Error 1");
     result.IsSuccess.Should().Be(false);
     result.Status.Should().Be(ResultStatus.Error); // <- Status changed to Error

     // clearing the errors (still remain one Validation Error, so it's Invalid)
     result.Errors.Clear();
     result.IsSuccess.Should().Be(false);
     result.Status.Should().Be(ResultStatus.Invalid); // <- Status changed to Invalid

     // clearing the validation errors. It should revert back to the initial status
     result.ValidationErrors.Clear();
     result.IsSuccess.Should().Be(true);
     result.Status.Should().Be(ResultStatus.Ok); // <- reverted back to its initial state
 }

[ardalis]

I'll bring this in separately since it's breaking change.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Ardalis.Result.AspNetCore	54%	60%	159	➖
Ardalis.Result.Sample.Core	38%	38%	63	❌
Ardalis.Result.SampleWeb	66%	50%	43	➖
Ardalis.Result	38%	24%	137	❌
Ardalis.Result.FluentValidation	0%	0%	6	❌
Summary	48% (497 / 1041)	45% (114 / 256)	408	❌