Invert the y-axis for 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.

[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!
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