trace2: add exit event to UI helpers

GCM's UI helpers are connected to the TRACE2 system via the Start() call
in ApplicationBase.cs. Since this call records Version and Start
events, ensure a corresponding Exit event is called before the helper
process completes.

Author: ldennington

src/shared/Atlassian.Bitbucket.UI.Avalonia/Program.cs

@@ -55,6 +55,7 @@ private static void AppMain(object o)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/shared/Git-Credential-Manager.UI.Avalonia/Program.cs

@@ -55,6 +55,7 @@ private static void AppMain(object o)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/shared/Git-Credential-Manager/Program.cs

@@ -29,7 +29,7 @@ public static void Main(string[] args)
                         );
                     }
                 }
-                
+
                 //
                 // Git Credential Manager's executable used to be named "git-credential-manager-core" before
                 // dropping the "-core" suffix. In order to prevent "helper not found" errors for users who

src/shared/GitHub.UI.Avalonia/Program.cs

@@ -57,6 +57,7 @@ private static void AppMain(object o)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/shared/GitLab.UI.Avalonia/Program.cs

@@ -54,6 +54,7 @@ private static void AppMain(object o)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/windows/Atlassian.Bitbucket.UI.Windows/Program.cs

@@ -28,6 +28,7 @@ public static async Task Main(string[] args)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/windows/Git-Credential-Manager.UI.Windows/Program.cs

@@ -28,6 +28,7 @@ public static async Task Main(string[] args)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/windows/GitHub.UI.Windows/Program.cs

@@ -30,6 +30,7 @@ public static async Task Main(string[] args)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }

src/windows/GitLab.UI.Windows/Program.cs

@@ -28,6 +28,7 @@ public static async Task Main(string[] args)
                     .GetAwaiter()
                     .GetResult();
 
+                context.Trace2.Stop(exitCode);
                 Environment.Exit(exitCode);
             }
         }