DataFactoryTestingFrameworkExpressionsEvaluator adds status property even if None is set.

Open src/data_factory_testing_framework/_pythonnet/data_factory_testing_framework_expressions_evaluator.py around line 40 and inspect how activity result properties are added. Reproduce the expression-evaluation case described in the issue, then verify that properties set to None are omitted while non-None properties remain available.

We have scenarios where certain Activity outputs (like status as described in #162 ) are not present on the Activity Outputs.

Currently neither functional tests nor activity tests can capture these scenarios because we add the status always to the activity results (see https://github.com/microsoft/data-factory-testing-framework/blob/main/src/data_factory_testing_framework/_pythonnet/data_factory_testing_framework_expressions_evaluator.py#L40).

The expression evaluator returns a error we can handle to mimic the behaviour:

>           raise Exception(f"Unknown error: {e}") from e
E           Exception: Unknown error: The template language expression 'contains(
E             createArray(
E               activity('Fail').status,
E               activity('Notebook').status
E             ),
E             'Failed'
E           )' cannot be evaluated because property 'status' doesn't exist, available properties are 'output, error'. Please see https://aka.ms/logicexpressions for usage details.
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionTextExpression.SelectObjectProperty(JObject root, JToken property, Boolean safeDereference)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionTextExpression.SelectProperty(JToken root, TemplateDereferenceExpression[] dereferences, TemplateExpressionEvaluationContext context, Boolean failOnError)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionTextExpression.EvaluateRootExpression(TemplateExpressionEvaluationContext context, Boolean failOnError, ISkippableEnumerator`1 parameterValues, Int32 parametersCount)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionExpression.EvaluateExpression(TemplateExpressionEvaluationContext context, Boolean failOnError)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionExpression.LazyParameterEnumerator.MoveNext(Int32 skip)
E              at Microsoft.Azure.Workflows.Templates.ISkippableEnumeratorExtensions.ToEnumerable[T](ISkippableEnumerator`1 enumerator)+MoveNext()
E              at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
E              at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateExpressionBuiltInFunctions.EvaluateFunction(String functionName, ISkippableEnumerator`1 parameters, Int32 parametersCount, Boolean preserveAnnotations)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateExpressionEvaluationHelper.EvaluateFunction(String functionName, ISkippableEnumerator`1 parameters, Int32 parametersCount)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionTextExpression.EvaluateRootExpression(TemplateExpressionEvaluationContext context, Boolean failOnError, ISkippableEnumerator`1 parameterValues, Int32 parametersCount)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionExpression.EvaluateExpression(TemplateExpressionEvaluationContext context, Boolean failOnError)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionExpression.LazyParameterEnumerator.MoveNext(Int32 skip)
E              at Microsoft.Azure.Workflows.Templates.ISkippableEnumeratorExtensions.ToEnumerable[T](ISkippableEnumerator`1 enumerator)+MoveNext()
E              at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
E              at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateExpressionBuiltInFunctions.EvaluateFunction(String functionName, ISkippableEnumerator`1 parameters, Int32 parametersCount, Boolean preserveAnnotations)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateExpressionEvaluationHelper.EvaluateFunction(String functionName, ISkippableEnumerator`1 parameters, Int32 parametersCount)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionTextExpression.EvaluateRootExpression(TemplateExpressionEvaluationContext context, Boolean failOnError, ISkippableEnumerator`1 parameterValues, Int32 parametersCount)
E              at Microsoft.Azure.Workflows.Templates.Expressions.TemplateFunctionExpression.EvaluateExpression(TemplateExpressionEvaluationContext context, Boolean failOnError)
E              at Microsoft.Azure.Workflows.Templates.Helpers.TemplateExpressionsHelper.EvaluateTemplateLanguageExpression(String expression, TemplateExpressionEvaluationContext evaluationContext)
E              at Microsoft.Azure.DataFactoryTestingFramework.Expressions.Evaluator.EvaluateExpression(String expression, String parametersJson, String variablesJson, String itemValueJson, String activityValuesJson)
E              at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
E              at System.Reflection.MethodBaseInvoker.InvokeWithManyArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

Proposed solution:

Only add the add properties if they are set to anything other than None.