FIX: Also inset the Listen block in PickControl mode [UUM-150217]

Add a 3px leading inset before the "Listen" toggle block in DrawSearchFieldControl so it is no longer flush against the popup's left edge in PickControl mode.

Jira: https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-150217

Author: Pauliusd01

Packages/com.unity.inputsystem/InputSystem/Editor/ControlPicker/InputControlPickerDropdown.cs

@@ -575,6 +575,7 @@ internal override string DrawSearchFieldControl(string searchString)
                     // When picking controls, have a "Listen" button that allows listening for input.
                     if (m_Owner.m_Mode == InputControlPicker.Mode.PickControl)
                     {
+                        GUILayout.Space(3f);
                         using (new EditorGUILayout.VerticalScope(GUILayout.MaxWidth(50)))
                         {
                             GUILayout.Space(4);