This type will be used to store mesh edges in #106638, but it could be used for anything else too. This commit adds support for: - The new type in the Python API - Editing the type in the edit mode "Attribute Set" operator - Rendering the type in EEVEE and Cycles for all geometry types - Geometry nodes attribute interpolation and mixing - Viewing the type in the spreadsheet and using row filters The attribute uses the `blender::int2` type in most code, and the `vec2i` DNA type in C code when necessary. The enum names are based on `INT32_2D` for consistency with `INT8` and `INT32`. Pull Request: blender/blender#106677