Atom Tools: Restoring idle behavior for viewport input behavior controller

Signed-off-by: Guthrie Adams <guthadam@amazon.com>

Gems/Atom/Tools/AtomToolsFramework/Code/Source/Viewport/ViewportInputBehaviorController/IdleBehavior.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/IdleBehavior.h>
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/ViewportInputBehaviorControllerInterface.h>
+
+namespace AtomToolsFramework
+{
+    IdleBehavior::IdleBehavior(ViewportInputBehaviorControllerInterface* controller)
+        : ViewportInputBehavior(controller)
+    {
+    }
+} // namespace AtomToolsFramework

Gems/Atom/Tools/AtomToolsFramework/Code/Source/Viewport/ViewportInputBehaviorController/ViewportInputBehaviorController.cpp

@@ -280,8 +280,14 @@ namespace AtomToolsFramework
     void ViewportInputBehaviorController::EvaluateControlBehavior()
     {
         auto it = m_behaviorMap.find(m_keys);
+        if (it == m_behaviorMap.end())
+        {
+            it = m_behaviorMap.find(None);
+        }
+
         AZStd::shared_ptr<ViewportInputBehavior> nextBehavior =
             it != m_behaviorMap.end() ? it->second : AZStd::shared_ptr<ViewportInputBehavior>();
+
         if (m_behavior != nextBehavior)
         {
             if (m_behavior)