Add scenes similar to deferred_rendering to 3d testbed

[hukasu]

Objective

The deferred_rendering example is frequently broken, adding it to the testbed will warn PRs that break it.

Solution

Add scenes similar to deferred_rendering to 3d testbed

Testing

cargo run --example testbed_3d --features="bevy_ci_testing"

Showcase

Screenshots for the new scenes
Forward

ForwardPrepass

Deferred

TODO

• Merge conflicts
• Limit CI

[hukasu]

simplyfied the test and added one more test to try and catch this issue with parallax #16679 (comment)

[hukasu]

Screenshot of the RemoveForwardPrepass scene on 5cc3f47, no particular reason for the choice of the commit, it was just an old commit that i knew that the parallax was broken

[alice-i-cecile]

Strongly in favor of this general direction. I'll probably defer to @mockersf on the exact testing details and the rendering folks on what should be shown though.

[hukasu]

@mockersf and @IceSentry will instruct me on how to filter this so that it is not run on EVERY PR

[mockersf]

This feels a bit too much on the different passes when we're not doing a lot of other things in 3d tests, and it increases the testbed_3d execution time from 20 seconds to 1m10.

Maybe it's a better candidate to when we're able to select tests based on PR label

[mockersf]

@mockersf and @IceSentry will instruct me on how to filter this so that it is not run on EVERY PR

not possible at the moment

[hukasu]

so it is S-Blocked until then?

[BenjaminBrienen]

triage: Has merge conflicts, still blocked