Invert the y-axis of the local coordinate space in extract_text2d_sprite

[ickshonpe]

Objective

We've got two parallel text renderings implementations, one for UI and one for 2d, that we try to keep feature equivalent.
bevy_ui and bevy_text use coordinates increasing downwards, but bevy_sprite uses coordinates increasing upwards.
In the extract_text2d_sprite text extraction function each y-coordinate is negated individually. If instead, in extract_text2d_sprite, we invert the y-axis for each text layout's local coordinate space, then the function can be made to more closely match bevy_ui_render's extraction code. Which should make it easier to maintain and extend the parallel implementations.

Fixes #21693

Solution

Invert the y-axis for the local coordinate space instead of negating each glyph’s y value. Flip the glyph sprites so their orientation is unchanged.

Testing

If this is correct, the output from the text2d example and testbed_2d's text scenes should be unchanged.

[github-actions]

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-21694

If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

[kfc35]

Is there a reason why flip_y is not set to true for the has_strikethrough and has_underline portions?

I’m very new here and just trying to understand things better; this is not a blocking comment!

[ickshonpe]

Is there a reason why flip_y is not set to true for the has_strikethrough and has_underline portions?

I’m very new here and just trying to understand things better; this is not a blocking comment!

The underline and strikethrough lines are untextured, so flip_y doesn't do anything.

[kfc35]

I checked out the branch and tested with the two examples mentioned, text2d and testbed. Both look the same between main and here 👍