Resizes the session's target and its map.
The session renders at the map's scale factor. Release every acquired frame first.
See mln_render_session_resize in the
C API reference.
Errors:
Status.unsupported when the session renders into a borrowed ring. Give
it new textures of the new size instead.
The commands of a RenderSessionHandle that discard their outcomes: each returns once native code accepts it and allocates no completion. A later completion on the same map fences them.