Snap-to-view should change the camera mode to orthographic

## What problem does this solve or what need does it fill?

Snap-to-view, added in https://github.com/bevyengine/bevy/pull/23674, is very useful for seeing how things line up from each of the standard axis directions.

However, it's much easier to see if things are correct if we're using an orthographic perspective: vanishing points distort things in ways you don't want.

## What solution would you like?

Swap to orthographic perspectives when you use the snap-to-view functionality.

Swap back when you change the angle of the camera in another way.

Cache the old projection inside the free camera controller so then you can restore the old defaults.

## Additional context

This is the standard behavior in e.g. Blender.