This fixes part of the tests

  Broadly, the tests were broken by #7489 because there were no _startupActions. They relied on the removed codepath that assumed wt.exe always set actions, or `AppCommandlineArgs::ValidateStartupCommands` created one by default.

  These tests are still broken:
  * `TerminalAppLocalTests::TabTests::TryZoomPane [Failed]`
  * `TerminalAppLocalTests::TabTests::MoveFocusFromZoomedPane [Failed]`
  * `TerminalAppLocalTests::TabTests::CloseZoomedPane [Failed]`

  Re:#9659

src/cascadia/LocalTests_TerminalApp/TabTests.cpp

@@ -257,9 +257,18 @@ namespace TerminalAppLocalTests
         result = RunOnUIThread([&page]() {
             VERIFY_IS_NOT_NULL(page);
             VERIFY_IS_NOT_NULL(page->_settings);
+            // DebugBreak();
             page->Create();
             Log::Comment(L"Create()'d the page successfully");
 
+            // Build the NewTab action from the values we've parsed on the commandline.
+            NewTerminalArgs newTerminalArgs{};
+            NewTabArgs args{ newTerminalArgs };
+            ActionAndArgs newTabAction{ ShortcutAction::NewTab, args };
+            // push the arg onto the front
+            page->_startupActions.Append(newTabAction);
+            Log::Comment(L"Added a single newTab action");
+
             auto app = ::winrt::Windows::UI::Xaml::Application::Current();
 
             winrt::TerminalApp::TerminalPage pp = *page;
@@ -276,8 +285,9 @@ namespace TerminalAppLocalTests
             // In the real app, this isn't a problem, but doesn't happen
             // reliably in the unit tests.
             Log::Comment(L"Ensure we set the first tab as the selected one.");
-            auto tab = page->_GetTerminalTabImpl(page->_tabs.GetAt(0));
-            page->_tabView.SelectedItem(tab->TabViewItem());
+            auto tab = page->_tabs.GetAt(0);
+            auto tabImpl = page->_GetTerminalTabImpl(tab);
+            page->_tabView.SelectedItem(tabImpl->TabViewItem());
             page->_UpdatedSelectedTab(0);
         });
         VERIFY_SUCCEEDED(result);