This contains the basis of the new overlay engine.
Only a few overlays are ported for proof of concept of the new design.
This new design unifies the selection drawing with the overlay-next engine.
It now becomes responsible of selection in object mode.
For this we create a dedicated shader module that patches the shaders
for selection.
Note that the gizmo selection still uses the occlusion queries and edit-mode
the current selection engine (select_engine.c).
Related task #102179
Related task #102177
Co-authored-by: Clément Foucault <foucault.clem@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/107734
9ae2dd577a