Remove all references to old CGrid system (#672)

* add overload to ActionManager to support capturing an AZStd::function

* move snapping settings to new settings registry

* remove unneeded reference in ViewportSettings

* move viewport setting function implementations to .cpp file

* add more sensible default values for snapping

* fix variable name for angle snapping

* remove const from function prototype value parameters

* add import/export api for free functions

* change from std::bind to a lambda

* remove redundant const for constexpr string_view

* add AZStd alias for std::abs

* restore grid and angle snapping

* add overload to ActionManager to support capturing an AZStd::function

* remove old legacy CGrid code

* fix build after merge

* review feedback changes - remove 1.0f multiplies

Code/Sandbox/Editor/Objects/AxisGizmo.cpp

@@ -18,7 +18,6 @@
 // Editor
 #include "Viewport.h"
 #include "GizmoManager.h"
-#include "Grid.h"
 #include "ViewManager.h"
 #include "Settings.h"
 #include "RenderHelpers/AxisHelper.h"
@@ -244,7 +243,8 @@ Matrix34 CAxisGizmo::GetTransformation(RefCoordSys coordSys, IDisplayViewport* v
             break;
         case COORDS_USERDEFINED:
         {
-            Matrix34 userTM = GetIEditor()->GetViewManager()->GetGrid()->GetMatrix();
+            Matrix34 userTM;
+            userTM.SetIdentity();
             userTM.SetTranslation(m_object->GetWorldTM().GetTranslation());
             return userTM;
         }