Manually close tabs when they're closed while dragging them

  ## Summary of the Pull Request

  When we're dragging the tab around, if you execute a `ClosePane`/`CloseTab`, then we should make sure to actually activate a new tab, so that focus doesn't just fall into the void.

  ## References

  * This is almost exactly #5799, but with rearranging tabs

  ## PR Checklist
  * [x] Closes #5559
  * [x] I work here
  * [ ] Tests added/passed
  * [n/a] Requires documentation to be updated

  ## Detailed Description of the Pull Request / Additional comments
  We suppress `_OnTabItemsChanged` events during a rearrange, so if a tab is closed while we're rearranging tabs, the we don't fire the `SelectionChanged` event that we usually do during a close that would select the new tab.

  ## Validation Steps Performed
  * Tested manually
    - Confirmed that tragging a tab out, closing it, then dragging it back in does nothing.

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -854,13 +854,17 @@ namespace winrt::TerminalApp::implementation
         {
             _lastTabClosedHandlers(*this, nullptr);
         }
-        else if (_isFullscreen)
+        else if (_isFullscreen || _rearranging)
         {
             // GH#5799 - If we're fullscreen, the TabView isn't visible. If it's
             // not Visible, it's _not_ going to raise a SelectionChanged event,
             // which is what we usually use to focus another tab. Instead, we'll
             // have to do it manually here.
             //
+            // GH#5559 Similarly, we suppress _OnTabItemsChanged events during a
+            // rearrange, so if a tab is closed while we're rearranging tabs, do
+            // this manually.
+            //
             // We can't use
             //   auto selectedIndex = _tabView.SelectedIndex();
             // Because this will always return -1 in this scenario unfortunately.
@@ -885,6 +889,15 @@ namespace winrt::TerminalApp::implementation
             auto newSelectedTab{ _GetStrongTabImpl(newSelectedIndex) };
             _tabView.SelectedItem(newSelectedTab->GetTabViewItem());
         }
+
+        // GH#5559 - If we were in the middle of a drag/drop, end it by clearing
+        // out our state.
+        if (_rearranging)
+        {
+            _rearranging = false;
+            _rearrangeFrom = std::nullopt;
+            _rearrangeTo = std::nullopt;
+        }
     }
 
     // Method Description: