Previously, it was not possible to see detailed information about instances in
the spreadsheet. Only the attributes on the top level instances were shown. Now,
all nested instances can be inspected too.
Combined with #114910 this will make inspecting more complex geometry with the
spreadsheet much more feasible. It's also an important part of integrating
grease pencil into geometry nodes because it makes it more obvious how layers
are converted to curve instances.
The data-selection is split into two separate tree views now. One that selects
the geometry from the instance tree, and one that's used to select the geometry
component and domain within that geometry. We found that this works better than
combining both tree views into one (we tried that in #124186).
Pull Request: https://projects.blender.org/blender/blender/pulls/125293
071b18a3cc