test: `TimelineStepsFeature.AddAppointmentToTimeline`

The test `Capgemini.PowerApps.SpecFlowBindings.UiTests.TimelineStepsFeature.AddAppointmentToTimeline` is failing.

```
Test method Capgemini.PowerApps.SpecFlowBindings.UiTests.TimelineStepsFeature.AddAppointmentToTimeline threw exception:
OpenQA.Selenium.NoSuchElementException: Field with name description does not exist.

at Microsoft.Dynamics365.UIAutomation.Browser.BrowserCommand`1.Execute[T1,T2,T3,T4,T5,T6,T7,T8,T9](IWebDriver driver, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6, T7 p7, T8 p8, T9 p9)
at Microsoft.Dynamics365.UIAutomation.Browser.BrowserCommand`1.Execute(IWebDriver driver)
at Microsoft.Dynamics365.UIAutomation.Browser.BrowserPage.Execute[TResult](BrowserCommandOptions options, Func`2 delegate)
at Microsoft.Dynamics365.UIAutomation.Api.UCI.Timeline.AddAppointment(String subject, String location, String duration, String description)
at Capgemini.PowerApps.SpecFlowBindings.Steps.TimelineSteps.WhenIAddAnAppointmentToTheTimeline(String subject, String description, String duration, String location) in \bindings\src\Capgemini.PowerApps.SpecFlowBindings\Steps\TimelineSteps.cs:line 27
at TechTalk.SpecFlow.Bindings.BindingInvoker.InvokeBinding(IBinding binding, IContextManager contextManager, Object[] arguments, ITestTracer testTracer, TimeSpan& duration)
at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.ExecuteStepMatch(BindingMatch match, Object[] arguments)
at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.ExecuteStep(IContextManager contextManager, StepInstance stepInstance)
at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.OnAfterLastStep()
```

https://dev.azure.com/capgeminiuk/GitHub%20Support/_build/results?buildId=8397&view=ms.vss-test-web.build-test-results-tab&runId=1015498&resultId=100161&paneView=debug

Start with the failing TimelineStepsFeature.AddAppointmentToTimeline test and the linked build result, then inspect bindings/src/Capgemini.PowerApps.SpecFlowBindings/Steps/TimelineSteps.cs at line 27. Trace the AddAppointment call and the missing description field reported by the exception. Done means the test runs successfully without the NoSuchElementException.

Written by the indexing model from the issue text.