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: https://projects.blender.org/blender/blender/pulls/106677
988f23cec3