During multiview rendering the `cryptomatte_accum_buffer` is not cleared between the views and leaves artifacts on the next view to be rendered. This change clears the accum buffer when it already exists and will be reused for the next view.
During multiview rendering the `cryptomatte_accum_buffer` is not cleared between the views and leaves artifacts on the next view to be rendered. This change clears the accum buffer when it already exists and will be reused for the next view.