TestRunRequestEventsRegistrar null in run specific tests

[vagisha-nidhi]

Description

Test run events registrar is null in case of run selected scenario causing the following error:

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
Microsoft.VisualStudio.TestPlatform.CommandLine.TestPlatformHelpers.TestRequestManager.CheckSourcesForCompatibility(Framework chosenFramework, Architecture chosenPlatform, IDictionary`2 sourcePlatforms, IDictionary`2 sourceFrameworks, IBaseTestEventsRegistrar registrar)
Microsoft.VisualStudio.TestPlatform.CommandLine.TestPlatformHelpers.TestRequestManager.UpdateRunSettingsIfRequired(String runsettingsXml, List`1 sources, IBaseTestEventsRegistrar registrar, String& updatedRunSettingsXml)
Microsoft.VisualStudio.TestPlatform.CommandLine.TestPlatformHelpers.TestRequestManager.RunTests(TestRunRequestPayload testRunRequestPayload, ITestHostLauncher testHostLauncher, ITestRunEventsRegistrar testRunEventsRegistrar, ProtocolConfig protocolConfig)
Microsoft.VisualStudio.TestPlatform.CommandLine.Processors.RunSpecificTestsArgumentExecutor.ExecuteSelectedTests()
Microsoft.VisualStudio.TestPlatform.CommandLine.Processors.RunSpecificTestsArgumentExecutor.Execute()
Microsoft.VisualStudio.TestPlatform.CommandLine.Executor.ExecuteArgumentProcessor(IArgumentProcessor processor, Int32& exitCode)
Microsoft.VisualStudio.TestPlatform.CommandLine.Executor.Execute(String[] args)
Microsoft.VisualStudio.TestPlatform.CommandLine.Program.Main(String[] args)

[singhsarab]

Test this please