Allow gizmos to render behind sprites

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

Currently, when using a 2d camera, gizmos always draw in front of all entities. This is annoying if you want to, for example, use a grid gizmo to help debug the grid entities can move on, but want the actual entities to render in front of the grid.

## What solution would you like?

When rendering a gizmo to a 2d camera, if the gizmo uses a Vec3 for its position (*_3d gizmos), consider this properly.

## What alternative(s) have you considered?

(ab)using the depth_bias for this, but this would make any explicit ordering quite hard

## Additional context

Example of issues: https://learnbevy.com/playground?share=d339a3268b24ccc1330ba9e0698430f3d3133240106e871ac687b36721ceb934

related to:
- https://github.com/bevyengine/bevy/issues/9308
- https://github.com/bevyengine/bevy/pull/9129