This adds support for showing various stats of volume grids in the spreadsheet:
* Extent: Number of voxels in each direction of the bounding box of the grid.
* Voxels: Total number of active voxels in the grid. This includes all voxels
which are stored in tiles (e.g. one leaf tile contains 512 voxels).
* Leaf Voxels: Number of active voxels stored in leaf nodes. This does not
contain any voxels that are part of tiles.
* Tiles: Number of active tiles in the grid.
* Size: Estimated size of the volume grid in memory.
All these stats are cached on the volume grid now. A new `tag_tree_changed`
method has been added to invalidate the cache. Computing these stats is not
cheap (but not more than a few ms even for large grids). That mainly means that
we can't do it for socket inspection because that would cause too much overhead.
However, doing it just for the grids that are currently visible in the
spreadsheet seems fine and useful.
This also adds some general improvements to the spreadsheet:
* Support `int64_t` and `int3` columns.
* Draw ints with thousand separators.
* Support showing ints as number of bytes such as `23 MB`.
Pull Request: https://projects.blender.org/blender/blender/pulls/147191
9d20c8d3c8