FIX: Control Schemes dropdown keeps showing a deleted scheme name after the last scheme is removed [UUM-141563] (#2463)

Author: Pauliusd01

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - Empty foldouts are no longer shown for processors and interactions that have no settings (e.g. "Invert") [UUM-144325](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-144325)
 - Fixed the Input Actions editor toolbar buttons being clipped when the Action Properties panel grew tall enough to show a scrollbar
+- Fixed the Control Schemes dropdown in the Input Actions editor continuing to display a deleted scheme's name after the last control scheme was removed, instead of resetting to "No Control Schemes" until the asset was saved or the editor reopened. [UUM-141563](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-141563)
 - Fixed the Input Debugger window (Window > Analysis > Input Debugger) being resizable arbitrarily small until its toolbar and device/action/layout tree view were no longer usably visible; it now enforces a minimum window size [UUM-137119](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-137119)
 - Fixed the Action Maps list in the Input Actions editor losing keyboard focus after deleting a map, so that Delete, Duplicate, and arrow-key navigation kept working on the auto-selected replacement map without requiring an extra click [UUM-147152](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-147152)
 

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Views/InputActionsEditorView.cs

@@ -180,6 +180,10 @@ private void SetUpControlSchemesMenu(ViewState viewState)
                         viewState.selectedControlSchemeIndex == i ? DropdownMenuAction.Status.Checked : DropdownMenuAction.Status.Normal));
                 m_ControlSchemesToolbar.menu.AppendSeparator();
             }
+            else
+            {
+                m_ControlSchemesToolbar.text = "No Control Schemes";
+            }
 
             m_ControlSchemesToolbar.menu.AppendAction("Add Control Scheme...", _ => AddOrUpdateControlScheme(rootElement));
             m_ControlSchemesToolbar.menu.AppendAction("Edit Control Scheme...", _ => AddOrUpdateControlScheme(rootElement, true),