This adds support for having viewer nodes in closures. The code attempt to
detect where the closure is evaluated and shows the data from there.
If the closure is evaluated in multiple Evaluate Closure nodes, currently it
just picks the first one it finds. Support for more user control in this case
may be added a bit later. If the Evaluate Closure node is in e.g. the repeat or
foreach zone, it will automatically use the inspection index of that zone to
determine what evaluation to look at specifically.
Overall, not too much had to change conceptually to support viewers in closures.
Just some code like converting between viewer paths and compute contexts had to
be generalized a little bit.
Pull Request: https://projects.blender.org/blender/blender/pulls/137625
a0444a5a2d