Update coordinates if r-adaptation

[jwallwork23]

If both the dm_plex_metric_no_insert and dm_plex_metric_no_swap options are set then [Par]Mmg will only apply $r$-adaptation (mesh movement). In that case the output mesh will have the same topology as the input mesh so we could just update the coordinates of the input mesh rather than creating a new one.

[ddundo]

@jwallwork23 would it make sense to do this in animate instead of goalie? Perhaps we could have animate.adapt.adapt accept a kwarg for it

[jwallwork23]

Oops I meant to open this in Animate indeed, will move it now. Thanks @ddundo.