... if only a single view is enabled
Logic for touching placeholder files in `RE_RenderAnim` uses
`BKE_scene_multiview_filepath_get` (no matter if only a single view is
enabled), but logic in `BKE_image_render_write` falls back to using the
"regular" filepath (once gotten from `BKE_image_path_from_imformat`) if
there are less than two views.
That would also break the behavior of "Skip Overwrite".
Digging in git history is a bit hard, so not exactly sure why this was
added, but this PR changes behavior so that
`BKE_scene_multiview_filepath_get` is always used (even for a single
(non-empty) view. Done by implementing `RE_ResultIsMultiView`
Pull Request: https://projects.blender.org/blender/blender/pulls/138507