Allow Mirror support for variants

Use variants heavily across files as they’ve become so ubiquitous and find the lack of mirroring really tough to prototype and move quick. Have to drag it all out and see it on the device.

Following this, I find using screens as variants super productive as it lets us have all the screen states with variants. But as they are not supported by Mirror or prototypes, its again dragging it all out and then doing it again.

Think its a big productivity gain if this works