RNA: Object.select_set use boolean, only select

- Was setting active state, making it necessary to backup/restore
  active object in cases where this isn't needed.
  Existing scripts are explicitly setting the active object when needed.

- Use a boolean select arg (toggle selection wasn't used anywhere).

- Add an optional view layer argument since scripts should be able to
  operate outside the user context.

release/scripts/templates_py/operator_modal_view3d_raycast.py

@@ -67,7 +67,7 @@ def main(context, event):
     # now we have the object under the mouse cursor,
     # we could do lots of stuff but for the example just select.
     if best_obj is not None:
-        best_obj.select_set(action='SELECT')
+        best_obj.select_set(True)
         context.view_layer.objects.active = best_obj