This replaces the existing C API of `BLO_Write_IDBuffer` with a C++ API. This
helps because:
* No need for explicit freeing.
* Can use more generic `DynamicStackBuffer` utility instead of having a separate
implementation of that.
Additionally, the API is changed so that a new `BLO_Write_IDBuffer` is created
for each `ID` instead of reusing the same for multiple IDs. This simplifies the
code quite a bit and allows for better use of the RAII pattern.
I expect the performance to be the same as before. In theory, there could be a
small speedup, because the `BLO_Write_IDBuffer` is not allocated separately
anymore, but that should be negligible.
No functional changes are expected.
Pull Request: https://projects.blender.org/blender/blender/pulls/130452
3c4e46f067