Close PR creation view when PR submitted.

Author: grokys

src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs

@@ -115,6 +115,7 @@ public PullRequestCreationViewModel(
                 NavigateTo("/pulls?refresh=true");
                 Cancel.Execute();
                 draftStore.DeleteDraft(GetDraftKey(), string.Empty).Forget();
+                Close();
             });
 
             Cancel = ReactiveCommand.Create(() => { });