Avoid running out of attributes when multiple material slots use the same one.
Cleanup:
Removes the return value from drw_attributes_add_request since it shouldn't be modified afterward and it's never used.
Avoid making copies of DRW_AttributeRequest in drw_attributes_has_request.
Co-authored-by: Miguel Pozo <pragma37@gmail.com>
Pull Request #104709
In order to experiment with different storage types for `DRW_Attributes`
and for general cleanup (see #103343). Also move a curves header to C++.
Pull Request #104716
